Hi Babu, On 3/12/25 9:03 AM, Moger, Babu wrote: > Hi Reinette, > > On 3/12/25 10:07, Reinette Chatre wrote: >> Hi Babu, >> >> On 3/11/25 1:35 PM, Moger, Babu wrote: >>> Hi All, >>> >>> On 3/10/25 22:51, Reinette Chatre wrote: >>>> >>>> >>>> On 3/10/25 6:44 PM, Moger, Babu wrote: >>>>> Hi Tony, >>>>> >>>>> On 3/10/2025 6:22 PM, Luck, Tony wrote: >>>>>> On Mon, Mar 10, 2025 at 05:48:44PM -0500, Moger, Babu wrote: >>>>>>> Hi All, >>>>>>> >>>>>>> On 3/5/2025 1:34 PM, Moger, Babu wrote: >>>>>>>> Hi Peter, >>>>>>>> >>>>>>>> On 3/5/25 04:40, Peter Newman wrote: >>>>>>>>> Hi Babu, >>>>>>>>> >>>>>>>>> On Tue, Mar 4, 2025 at 10:49 PM Moger, Babu <babu.moger@xxxxxxx> wrote: >>>>>>>>>> >>>>>>>>>> Hi Peter, >>>>>>>>>> >>>>>>>>>> On 3/4/25 10:44, Peter Newman wrote: >>>>>>>>>>> On Mon, Mar 3, 2025 at 8:16 PM Moger, Babu <babu.moger@xxxxxxx> wrote: >>>>>>>>>>>> >>>>>>>>>>>> Hi Peter/Reinette, >>>>>>>>>>>> >>>>>>>>>>>> On 2/26/25 07:27, Peter Newman wrote: >>>>>>>>>>>>> Hi Babu, >>>>>>>>>>>>> >>>>>>>>>>>>> On Tue, Feb 25, 2025 at 10:31 PM Moger, Babu <babu.moger@xxxxxxx> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>> Hi Peter, >>>>>>>>>>>>>> >>>>>>>>>>>>>> On 2/25/25 11:11, Peter Newman wrote: >>>>>>>>>>>>>>> Hi Reinette, >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Fri, Feb 21, 2025 at 11:43 PM Reinette Chatre >>>>>>>>>>>>>>> <reinette.chatre@xxxxxxxxx> wrote: >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Hi Peter, >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> On 2/21/25 5:12 AM, Peter Newman wrote: >>>>>>>>>>>>>>>>> On Thu, Feb 20, 2025 at 7:36 PM Reinette Chatre >>>>>>>>>>>>>>>>> <reinette.chatre@xxxxxxxxx> wrote: >>>>>>>>>>>>>>>>>> On 2/20/25 6:53 AM, Peter Newman wrote: >>>>>>>>>>>>>>>>>>> On Wed, Feb 19, 2025 at 7:21 PM Reinette Chatre >>>>>>>>>>>>>>>>>>> <reinette.chatre@xxxxxxxxx> wrote: >>>>>>>>>>>>>>>>>>>> On 2/19/25 3:28 AM, Peter Newman wrote: >>>>>>>>>>>>>>>>>>>>> On Tue, Feb 18, 2025 at 6:50 PM Reinette Chatre >>>>>>>>>>>>>>>>>>>>> <reinette.chatre@xxxxxxxxx> wrote: >>>>>>>>>>>>>>>>>>>>>> On 2/17/25 2:26 AM, Peter Newman wrote: >>>>>>>>>>>>>>>>>>>>>>> On Fri, Feb 14, 2025 at 8:18 PM Reinette Chatre >>>>>>>>>>>>>>>>>>>>>>> <reinette.chatre@xxxxxxxxx> wrote: >>>>>>>>>>>>>>>>>>>>>>>> On 2/14/25 10:31 AM, Moger, Babu wrote: >>>>>>>>>>>>>>>>>>>>>>>>> On 2/14/2025 12:26 AM, Reinette Chatre wrote: >>>>>>>>>>>>>>>>>>>>>>>>>> On 2/13/25 9:37 AM, Dave Martin wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>> On Wed, Feb 12, 2025 at 03:33:31PM -0800, Reinette Chatre wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>> On 2/12/25 9:46 AM, Dave Martin wrote: >>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Wed, Jan 22, 2025 at 02:20:08PM -0600, Babu Moger wrote: >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> (quoting relevant parts with goal to focus discussion on new possible syntax) >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> I see the support for MPAM events distinct from the support of assignable counters. >>>>>>>>>>>>>>>>>>>>>>>>>>>> Once the MPAM events are sorted, I think that they can be assigned with existing interface. >>>>>>>>>>>>>>>>>>>>>>>>>>>> Please help me understand if you see it differently. >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Doing so would need to come up with alphabetical letters for these events, >>>>>>>>>>>>>>>>>>>>>>>>>>>> which seems to be needed for your proposal also? If we use possible flags of: >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> mbm_local_read_bytes a >>>>>>>>>>>>>>>>>>>>>>>>>>>> mbm_local_write_bytes b >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> Then mbm_assign_control can be used as: >>>>>>>>>>>>>>>>>>>>>>>>>>>> # echo '//0=ab;1=b' >/sys/fs/resctrl/info/L3_MON/mbm_assign_control >>>>>>>>>>>>>>>>>>>>>>>>>>>> # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_read_bytes >>>>>>>>>>>>>>>>>>>>>>>>>>>> <value> >>>>>>>>>>>>>>>>>>>>>>>>>>>> # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes >>>>>>>>>>>>>>>>>>>>>>>>>>>> <sum of mbm_local_read_bytes and mbm_local_write_bytes> >>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> One issue would be when resctrl needs to support more than 26 events (no more flags available), >>>>>>>>>>>>>>>>>>>>>>>>>>>> assuming that upper case would be used for "shared" counters (unless this interface is defined >>>>>>>>>>>>>>>>>>>>>>>>>>>> differently and only few uppercase letters used for it). Would this be too low of a limit? >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>> As mentioned above, one possible issue with existing interface is that >>>>>>>>>>>>>>>>>>>>>>>> it is limited to 26 events (assuming only lower case letters are used). The limit >>>>>>>>>>>>>>>>>>>>>>>> is low enough to be of concern. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> The events which can be monitored by a single counter on ABMC and MPAM >>>>>>>>>>>>>>>>>>>>>>> so far are combinable, so 26 counters per group today means it limits >>>>>>>>>>>>>>>>>>>>>>> breaking down MBM traffic for each group 26 ways. If a user complained >>>>>>>>>>>>>>>>>>>>>>> that a 26-way breakdown of a group's MBM traffic was limiting their >>>>>>>>>>>>>>>>>>>>>>> investigation, I would question whether they know what they're looking >>>>>>>>>>>>>>>>>>>>>>> for. >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> The key here is "so far" as well as the focus on MBM only. >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> It is impossible for me to predict what we will see in a couple of years >>>>>>>>>>>>>>>>>>>>>> from Intel RDT, AMD PQoS, and Arm MPAM that now all rely on resctrl interface >>>>>>>>>>>>>>>>>>>>>> to support their users. Just looking at the Intel RDT spec the event register >>>>>>>>>>>>>>>>>>>>>> has space for 32 events for each "CPU agent" resource. That does not take into >>>>>>>>>>>>>>>>>>>>>> account the "non-CPU agents" that are enumerated via ACPI. Tony already mentioned >>>>>>>>>>>>>>>>>>>>>> that he is working on patches [1] that will add new events and shared the idea >>>>>>>>>>>>>>>>>>>>>> that we may be trending to support "perf" like events associated with RMID. I >>>>>>>>>>>>>>>>>>>>>> expect AMD PQoS and Arm MPAM to provide related enhancements to support their >>>>>>>>>>>>>>>>>>>>>> customers. >>>>>>>>>>>>>>>>>>>>>> This all makes me think that resctrl should be ready to support more events than 26. >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> I was thinking of the letters as representing a reusable, user-defined >>>>>>>>>>>>>>>>>>>>> event-set for applying to a single counter rather than as individual >>>>>>>>>>>>>>>>>>>>> events, since MPAM and ABMC allow us to choose the set of events each >>>>>>>>>>>>>>>>>>>>> one counts. Wherever we define the letters, we could use more symbolic >>>>>>>>>>>>>>>>>>>>> event names. >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> Thank you for clarifying. >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> In the letters as events model, choosing the events assigned to a >>>>>>>>>>>>>>>>>>>>> group wouldn't be enough information, since we would want to control >>>>>>>>>>>>>>>>>>>>> which events should share a counter and which should be counted by >>>>>>>>>>>>>>>>>>>>> separate counters. I think the amount of information that would need >>>>>>>>>>>>>>>>>>>>> to be encoded into mbm_assign_control to represent the level of >>>>>>>>>>>>>>>>>>>>> configurability supported by hardware would quickly get out of hand. >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> Maybe as an example, one counter for all reads, one counter for all >>>>>>>>>>>>>>>>>>>>> writes in ABMC would look like... >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> (L3_QOS_ABMC_CFG.BwType field names below) >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> (per domain) >>>>>>>>>>>>>>>>>>>>> group 0: >>>>>>>>>>>>>>>>>>>>> counter 0: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>>>>> counter 1: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>>>>> group 1: >>>>>>>>>>>>>>>>>>>>> counter 2: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>>>>> counter 3: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>>>>> ... >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> I think this may also be what Dave was heading towards in [2] but in that >>>>>>>>>>>>>>>>>>>> example and above the counter configuration appears to be global. You do mention >>>>>>>>>>>>>>>>>>>> "configurability supported by hardware" so I wonder if per-domain counter >>>>>>>>>>>>>>>>>>>> configuration is a requirement? >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> If it's global and we want a particular group to be watched by more >>>>>>>>>>>>>>>>>>> counters, I wouldn't want this to result in allocating more counters >>>>>>>>>>>>>>>>>>> for that group in all domains, or allocating counters in domains where >>>>>>>>>>>>>>>>>>> they're not needed. I want to encourage my users to avoid allocating >>>>>>>>>>>>>>>>>>> monitoring resources in domains where a job is not allowed to run so >>>>>>>>>>>>>>>>>>> there's less pressure on the counters. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> In Dave's proposal it looks like global configuration means >>>>>>>>>>>>>>>>>>> globally-defined "named counter configurations", which works because >>>>>>>>>>>>>>>>>>> it's really per-domain assignment of the configurations to however >>>>>>>>>>>>>>>>>>> many counters the group needs in each domain. >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> I think I am becoming lost. Would a global configuration not break your >>>>>>>>>>>>>>>>>> view of "event-set applied to a single counter"? If a counter is configured >>>>>>>>>>>>>>>>>> globally then it would not make it possible to support the full configurability >>>>>>>>>>>>>>>>>> of the hardware. >>>>>>>>>>>>>>>>>> Before I add more confusion, let me try with an example that builds on your >>>>>>>>>>>>>>>>>> earlier example copied below: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> (per domain) >>>>>>>>>>>>>>>>>>>>> group 0: >>>>>>>>>>>>>>>>>>>>> counter 0: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>>>>> counter 1: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>>>>> group 1: >>>>>>>>>>>>>>>>>>>>> counter 2: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>>>>> counter 3: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>>>>> ... >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> Since the above states "per domain" I rewrite the example to highlight that as >>>>>>>>>>>>>>>>>> I understand it: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> group 0: >>>>>>>>>>>>>>>>>> domain 0: >>>>>>>>>>>>>>>>>> counter 0: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 1: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> domain 1: >>>>>>>>>>>>>>>>>> counter 0: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 1: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> group 1: >>>>>>>>>>>>>>>>>> domain 0: >>>>>>>>>>>>>>>>>> counter 2: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 3: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> domain 1: >>>>>>>>>>>>>>>>>> counter 2: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 3: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> You mention that you do not want counters to be allocated in domains that they >>>>>>>>>>>>>>>>>> are not needed in. So, let's say group 0 does not need counter 0 and counter 1 >>>>>>>>>>>>>>>>>> in domain 1, resulting in: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> group 0: >>>>>>>>>>>>>>>>>> domain 0: >>>>>>>>>>>>>>>>>> counter 0: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 1: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> group 1: >>>>>>>>>>>>>>>>>> domain 0: >>>>>>>>>>>>>>>>>> counter 2: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 3: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> domain 1: >>>>>>>>>>>>>>>>>> counter 2: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 3: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> With counter 0 and counter 1 available in domain 1, these counters could >>>>>>>>>>>>>>>>>> theoretically be configured to give group 1 more data in domain 1: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> group 0: >>>>>>>>>>>>>>>>>> domain 0: >>>>>>>>>>>>>>>>>> counter 0: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 1: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> group 1: >>>>>>>>>>>>>>>>>> domain 0: >>>>>>>>>>>>>>>>>> counter 2: LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 3: VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> domain 1: >>>>>>>>>>>>>>>>>> counter 0: LclFill,RmtFill >>>>>>>>>>>>>>>>>> counter 1: LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>>> counter 2: LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>>> counter 3: VictimBW >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> The counters are shown with different per-domain configurations that seems to >>>>>>>>>>>>>>>>>> match with earlier goals of (a) choose events counted by each counter and >>>>>>>>>>>>>>>>>> (b) do not allocate counters in domains where they are not needed. As I >>>>>>>>>>>>>>>>>> understand the above does contradict global counter configuration though. >>>>>>>>>>>>>>>>>> Or do you mean that only the *name* of the counter is global and then >>>>>>>>>>>>>>>>>> that it is reconfigured as part of every assignment? >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Yes, I meant only the *name* is global. I assume based on a particular >>>>>>>>>>>>>>>>> system configuration, the user will settle on a handful of useful >>>>>>>>>>>>>>>>> groupings to count. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Perhaps mbm_assign_control syntax is the clearest way to express an example... >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> # define global configurations (in ABMC terms), not necessarily in this >>>>>>>>>>>>>>>>> # syntax and probably not in the mbm_assign_control file. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> r=LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>>>>>>> w=VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> # legacy "total" configuration, effectively r+w >>>>>>>>>>>>>>>>> t=LclFill,RmtFill,LclSlowFill,RmtSlowFill,VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> /group0/0=t;1=t >>>>>>>>>>>>>>>>> /group1/0=t;1=t >>>>>>>>>>>>>>>>> /group2/0=_;1=t >>>>>>>>>>>>>>>>> /group3/0=rw;1=_ >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> - group2 is restricted to domain 0 >>>>>>>>>>>>>>>>> - group3 is restricted to domain 1 >>>>>>>>>>>>>>>>> - the rest are unrestricted >>>>>>>>>>>>>>>>> - In group3, we decided we need to separate read and write traffic >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> This consumes 4 counters in domain 0 and 3 counters in domain 1. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> I see. Thank you for the example. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> resctrl supports per-domain configurations with the following possible when >>>>>>>>>>>>>>>> using mbm_total_bytes_config and mbm_local_bytes_config: >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> t(domain 0)=LclFill,RmtFill,LclSlowFill,RmtSlowFill,VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>> t(domain 1)=LclFill,RmtFill,VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> /group0/0=t;1=t >>>>>>>>>>>>>>>> /group1/0=t;1=t >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Even though the flags are identical in all domains, the assigned counters will >>>>>>>>>>>>>>>> be configured differently in each domain. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> With this supported by hardware and currently also supported by resctrl it seems >>>>>>>>>>>>>>>> reasonable to carry this forward to what will be supported next. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> The hardware supports both a per-domain mode, where all groups in a >>>>>>>>>>>>>>> domain use the same configurations and are limited to two events per >>>>>>>>>>>>>>> group and a per-group mode where every group can be configured and >>>>>>>>>>>>>>> assigned freely. This series is using the legacy counter access mode >>>>>>>>>>>>>>> where only counters whose BwType matches an instance of QOS_EVT_CFG_n >>>>>>>>>>>>>>> in the domain can be read. If we chose to read the assigned counter >>>>>>>>>>>>>>> directly (QM_EVTSEL[ExtendedEvtID]=1, QM_EVTSEL[EvtID]=L3CacheABMC) >>>>>>>>>>>>>>> rather than asking the hardware to find the counter by RMID, we would >>>>>>>>>>>>>>> not be limited to 2 counters per group/domain and the hardware would >>>>>>>>>>>>>>> have the same flexibility as on MPAM. >>>>>>>>>>>>>> >>>>>>>>>>>>>> In extended mode, the contents of a specific counter can be read by >>>>>>>>>>>>>> setting the following fields in QM_EVTSEL: [ExtendedEvtID]=1, >>>>>>>>>>>>>> [EvtID]=L3CacheABMC and setting [RMID] to the desired counter ID. Reading >>>>>>>>>>>>>> QM_CTR will then return the contents of the specified counter. >>>>>>>>>>>>>> >>>>>>>>>>>>>> It is documented below. >>>>>>>>>>>>>> https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/24593.pdf >>>>>>>>>>>>>> Section: 19.3.3.3 Assignable Bandwidth Monitoring (ABMC) >>>>>>>>>>>>>> >>>>>>>>>>>>>> We previously discussed this with you (off the public list) and I >>>>>>>>>>>>>> initially proposed the extended assignment mode. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Yes, the extended mode allows greater flexibility by enabling multiple >>>>>>>>>>>>>> counters to be assigned to the same group, rather than being limited to >>>>>>>>>>>>>> just two. >>>>>>>>>>>>>> >>>>>>>>>>>>>> However, the challenge is that we currently lack the necessary interfaces >>>>>>>>>>>>>> to configure multiple events per group. Without these interfaces, the >>>>>>>>>>>>>> extended mode is not practical at this time. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Therefore, we ultimately agreed to use the legacy mode, as it does not >>>>>>>>>>>>>> require modifications to the existing interface, allowing us to continue >>>>>>>>>>>>>> using it as is. >>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> (I might have said something confusing in my last messages because I >>>>>>>>>>>>>>> had forgotten that I switched to the extended assignment mode when >>>>>>>>>>>>>>> prototyping with soft-ABMC and MPAM.) >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Forcing all groups on a domain to share the same 2 counter >>>>>>>>>>>>>>> configurations would not be acceptable for us, as the example I gave >>>>>>>>>>>>>>> earlier is one I've already been asked about. >>>>>>>>>>>>>> >>>>>>>>>>>>>> I don’t see this as a blocker. It should be considered an extension to the >>>>>>>>>>>>>> current ABMC series. We can easily build on top of this series once we >>>>>>>>>>>>>> finalize how to configure the multiple event interface for each group. >>>>>>>>>>>>> >>>>>>>>>>>>> I don't think it is, either. Only being able to use ABMC to assign >>>>>>>>>>>>> counters is fine for our use as an incremental step. My longer-term >>>>>>>>>>>>> concern is the domain-scoped mbm_total_bytes_config and >>>>>>>>>>>>> mbm_local_bytes_config files, but they were introduced with BMEC, so >>>>>>>>>>>>> there's already an expectation that the files are present when BMEC is >>>>>>>>>>>>> supported. >>>>>>>>>>>>> >>>>>>>>>>>>> On ABMC hardware that also supports BMEC, I'm concerned about enabling >>>>>>>>>>>>> ABMC when only the BMEC-style event configuration interface exists. >>>>>>>>>>>>> The scope of my issue is just whether enabling "full" ABMC support >>>>>>>>>>>>> will require an additional opt-in, since that could remove the BMEC >>>>>>>>>>>>> interface. If it does, it's something we can live with. >>>>>>>>>>>> >>>>>>>>>>>> As you know, this series is currently blocked without further feedback. >>>>>>>>>>>> >>>>>>>>>>>> I’d like to begin reworking these patches to incorporate Peter’s feedback. >>>>>>>>>>>> Any input or suggestions would be appreciated. >>>>>>>>>>>> >>>>>>>>>>>> Here’s what we’ve learned so far: >>>>>>>>>>>> >>>>>>>>>>>> 1. Assignments should be independent of BMEC. >>>>>>>>>>>> 2. We should be able to specify multiple event types to a counter (e.g., >>>>>>>>>>>> read, write, victimBM, etc.). This is also called shared counter >>>>>>>>>>>> 3. There should be an option to assign events per domain. >>>>>>>>>>>> 4. Currently, only two counters can be assigned per group, but the design >>>>>>>>>>>> should allow flexibility to assign more in the future as the interface >>>>>>>>>>>> evolves. >>>>>>>>>>>> 5. Utilize the extended RMID read mode. >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Here is my proposal using Peter's earlier example: >>>>>>>>>>>> >>>>>>>>>>>> # define event configurations >>>>>>>>>>>> >>>>>>>>>>>> ======================================================== >>>>>>>>>>>> Bits Mnemonics Description >>>>>>>>>>>> ==== ======================================================== >>>>>>>>>>>> 6 VictimBW Dirty Victims from all types of memory >>>>>>>>>>>> 5 RmtSlowFill Reads to slow memory in the non-local NUMA domain >>>>>>>>>>>> 4 LclSlowFill Reads to slow memory in the local NUMA domain >>>>>>>>>>>> 3 RmtNTWr Non-temporal writes to non-local NUMA domain >>>>>>>>>>>> 2 LclNTWr Non-temporal writes to local NUMA domain >>>>>>>>>>>> 1 mtFill Reads to memory in the non-local NUMA domain >>>>>>>>>>>> 0 LclFill Reads to memory in the local NUMA domain >>>>>>>>>>>> ==== ======================================================== >>>>>>>>>>>> >>>>>>>>>>>> #Define flags based on combination of above event types. >>>>>>>>>>>> >>>>>>>>>>>> t = LclFill,RmtFill,LclSlowFill,RmtSlowFill,VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>> l = LclFill, LclNTWr, LclSlowFill >>>>>>>>>>>> r = LclFill,RmtFill,LclSlowFill,RmtSlowFill >>>>>>>>>>>> w = VictimBW,LclNTWr,RmtNTWr >>>>>>>>>>>> v = VictimBW >>>>>>>>>>>> >>>>>>>>>>>> Peter suggested the following format earlier : >>>>>>>>>>>> >>>>>>>>>>>> /group0/0=t;1=t >>>>>>>>>>>> /group1/0=t;1=t >>>>>>>>>>>> /group2/0=_;1=t >>>>>>>>>>>> /group3/0=rw;1=_ >>>>>>>>>>> >>>>>>>>>>> After some inquiries within Google, it sounds like nobody has invested >>>>>>>>>>> much into the current mbm_assign_control format yet, so it would be >>>>>>>>>>> best to drop it and distribute the configuration around the filesystem >>>>>>>>>>> hierarchy[1], which should allow us to produce something more flexible >>>>>>>>>>> and cleaner to implement. >>>>>>>>>>> >>>>>>>>>>> Roughly what I had in mind: >>>>>>>>>>> >>>>>>>>>>> Use mkdir in a info/<resource>_MON subdirectory to create free-form >>>>>>>>>>> names for the assignable configurations rather than being restricted >>>>>>>>>>> to single letters. In the resulting directory, populate a file where >>>>>>>>>>> we can specify the set of events the config should represent. I think >>>>>>>>>>> we should use symbolic names for the events rather than raw BMEC field >>>>>>>>>>> values. Moving forward we could come up with portable names for common >>>>>>>>>>> events and only support the BMEC names on AMD machines for users who >>>>>>>>>>> want specific events and don't care about portability. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> I’m still processing this. Let me start with some initial questions. >>>>>>>>>> >>>>>>>>>> So, we are creating event configurations here, which seems reasonable. >>>>>>>>>> >>>>>>>>>> Yes, we should use portable names and are not limited to BMEC names. >>>>>>>>>> >>>>>>>>>> How many configurations should we allow? Do we know? >>>>>>>>> >>>>>>>>> Do we need an upper limit? >>>>>>>> >>>>>>>> I think so. This needs to be maintained in some data structure. We can >>>>>>>> start with 2 default configurations for now. >>>> >>>> There is a big difference between no upper limit and 2. The hardware is >>>> capable of supporting per-domain configurations so more flexibility is >>>> certainly possible. Consider the example presented by Peter in: >>>> https://lore.kernel.org/lkml/CALPaoCi0mFZ9TycyNs+SCR+2tuRJovQ2809jYMun4HtC64hJmA@xxxxxxxxxxxxxx/ >>>> >>>>>>>>>>> Next, put assignment-control file nodes in per-domain directories >>>>>>>>>>> (i.e., mon_data/mon_L3_00/assign_{exclusive,shared}). Writing a >>>>>>>>>>> counter-configuration name into the file would then allocate a counter >>>>>>>>>>> in the domain, apply the named configuration, and monitor the parent >>>>>>>>>>> group-directory. We can also put a group/resource-scoped assign_* file >>>>>>>>>>> higher in the hierarchy to make it easier for users who want to >>>>>>>>>>> configure all domains the same for a group. >>>>>>>>>> >>>>>>>>>> What is the difference between shared and exclusive? >>>>>>>>> >>>>>>>>> Shared assignment[1] means that non-exclusively-assigned counters in >>>>>>>>> each domain will be scheduled round-robin to the groups requesting >>>>>>>>> shared access to a counter. In my tests, I assigned the counters long >>>>>>>>> enough to produce a single 1-second MB/s sample for the per-domain >>>>>>>>> aggregation files[2]. >>>>>>>>> >>>>>>>>> These do not need to be implemented immediately, but knowing that they >>>>>>>>> work addresses the overhead and scalability concerns of reassigning >>>>>>>>> counters and reading their values. >>>>>>>> >>>>>>>> Ok. Lets focus on exclusive assignments for now. >>>>>>>> >>>>>>>>> >>>>>>>>>> >>>>>>>>>> Having three files—assign_shared, assign_exclusive, and unassign—for each >>>>>>>>>> domain seems excessive. In a system with 32 groups and 12 domains, this >>>>>>>>>> results in 32 × 12 × 3 files, which is quite large. >>>>>>>>>> >>>>>>>>>> There should be a more efficient way to handle this. >>>>>>>>>> >>>>>>>>>> Initially, we started with a group-level file for this interface, but it >>>>>>>>>> was rejected due to the high number of sysfs calls, making it inefficient. >>>>>>>>> >>>>>>>>> I had rejected it due to the high-frequency of access of a large >>>>>>>>> number of files, which has since been addressed by shared assignment >>>>>>>>> (or automatic reassignment) and aggregated mbps files. >>>>>>>> >>>>>>>> I think we should address this as well. Creating three extra files for >>>>>>>> each group isn’t ideal when there are more efficient alternatives. >>>>>>>> >>>>>>>>> >>>>>>>>>> >>>>>>>>>> Additionally, how can we list all assignments with a single sysfs call? >>>>>>>>>> >>>>>>>>>> That was another problem we need to address. >>>>>>>>> >>>>>>>>> This is not a requirement I was aware of. If the user forgot where >>>>>>>>> they assigned counters (or forgot to disable auto-assignment), they >>>>>>>>> can read multiple sysfs nodes to remind themselves. >>>>>>>> >>>>>>>> I suggest, we should provide users with an option to list the assignments >>>>>>>> of all groups in a single command. As the number of groups increases, it >>>>>>>> becomes cumbersome to query each group individually. >>>>>>>> >>>>>>>> To achieve this, we can reuse our existing mbm_assign_control interface >>>>>>>> for this purpose. More details on this below. >>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> The configuration names listed in assign_* would result in files of >>>>>>>>>>> the same name in the appropriate mon_data domain directories from >>>>>>>>>>> which the count values can be read. >>>>>>>>>>> >>>>>>>>>>> # mkdir info/L3_MON/counter_configs/mbm_local_bytes >>>>>>>>>>> # echo LclFill > info/L3_MON/counter_configs/mbm_local_bytes/event_filter >>>>>>>>>>> # echo LclNTWr > info/L3_MON/counter_configs/mbm_local_bytes/event_filter >>>>>>>>>>> # echo LclSlowFill > info/L3_MON/counter_configs/mbm_local_bytes/event_filter >>>>>>>>>>> # cat info/L3_MON/counter_configs/mbm_local_bytes/event_filter >>>>>>>>>>> LclFill >>>>>>>>>>> LclNTWr >>>>>>>>>>> LclSlowFill >>>>>>>>>> >>>>>>>>>> I feel we can just have the configs. event_filter file is not required. >>>>>>>>> >>>>>>>>> That's right, I forgot that we can implement kernfs_ops::open(). I was >>>>>>>>> only looking at struct kernfs_syscall_ops >>>>>>>>> >>>>>>>>>> >>>>>>>>>> #cat info/L3_MON/counter_configs/mbm_local_bytes >>>>>>>>>> LclFill <-rename these to generic names. >>>>>>>>>> LclNTWr >>>>>>>>>> LclSlowFill >>>>>>>>>> >>>>>>>>> >>>>>>>>> I think portable and non-portable event names should both be available >>>>>>>>> as options. There are simple bandwidth measurement mechanisms that >>>>>>>>> will be applied in general, but when they turn up an issue, it can >>>>>>>>> often lead to a more focused investigation, requiring more precise >>>>>>>>> events. >>>>>>>> >>>>>>>> I aggree. We should provide both portable and non-portable event names. >>>>>>>> >>>>>>>> Here is my draft proposal based on the discussion so far and reusing some >>>>>>>> of the current interface. Idea here is to start with basic assigment >>>>>>>> feature with options to enhance it in the future. Feel free to >>>>>>>> comment/suggest. >>>>>>>> >>>>>>>> 1. Event configurations will be in >>>>>>>> /sys/fs/resctrl/info/L3_MON/counter_configs/. >>>>>>>> >>>>>>>> There will be two pre-defined configurations by default. >>>>>>>> >>>>>>>> #cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_total_bytes >>>>>>>> LclFill, LclNTWr,LclSlowFill,VictimBM,RmtSlowFill,LclSlowFill,RmtFill >>>>>>>> >>>>>>>> #cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes >>>>>>>> LclFill, LclNTWr, LclSlowFill >>>>>>>> >>>>>>>> 2. Users will have options to update these configurations. >>>>>>>> >>>>>>>> #echo "LclFill, LclNTWr, RmtFill" > >>>>>>>> /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes >>>>>> >>>>>> This part seems odd to me. Now the "mbm_local_bytes" files aren't >>>>>> reporting "local_bytes" any more. They report something different, >>>>>> and users only know if they come to check the options currently >>>>>> configured in this file. Changing the contents without changing >>>>>> the name seems confusing to me. >>>>> >>>>> It is the same behaviour right now with BMEC. It is configurable. >>>>> By default it is mbm_local_bytes, but users can configure whatever they want to monitor using /info/L3_MON/mbm_local_bytes_config. >>>>> >>>>> We can continue the same behaviour with ABMC, but the configuration will be in /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes. >>>> >>>> This could be supported by following Peter's original proposal where the name >>>> of the counter configuration is provided by the user via a mkdir: >>>> https://lore.kernel.org/lkml/CALPaoCiii0vXOF06mfV=kVLBzhfNo0SFqt4kQGwGSGVUqvr2Dg@xxxxxxxxxxxxxx/ >>>> >>>> As he mentioned there could be pre-populated mbm_local_bytes/mbm_total_bytes. >>> >>> Sure. We can do that. I was thinking in the first phase, just provide the >>> default pre-defined configuration and option to update the configuration. >>> >>> We can add the mkdir support later. That way we can provide basic ABMC >>> support without too much code complexity with mkdir support. >> >> This is not clear to me how you envision the "first phase". Is it what you >> proposed above, for example: >> #echo "LclFill, LclNTWr, RmtFill" > >> /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes >> >> In above the counter configuration name is a file. > > Yes. That is correct. > > There will be two configuration files by default when resctrl is mounted > when ABMC is enabled. > /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_total_bytes > /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes > >> >> How could mkdir support be added to this later if there are already files present? > > We already have these directories when resctrl is mounted. > /sys/fs/resctrl/test/mon_data/mon_L3_00/mbm_total_bytes > /sys/fs/resctrl/test/mon_data/mon_L3_00/mbm_local_bytes > /sys/fs/resctrl/test/mon_data/mon_L3_01/mbm_total_bytes > /sys/fs/resctrl/test/mon_data/mon_L3_01/mbm_local_bytes > > We dont need "mkdir" support for default configurations. I was referring to the "mkdir" support for additional configurations that I understood you are thinking about adding later. For example, (copied from Peter's message https://lore.kernel.org/lkml/CALPaoCiii0vXOF06mfV=kVLBzhfNo0SFqt4kQGwGSGVUqvr2Dg@xxxxxxxxxxxxxx/): # mkdir info/L3_MON/counter_configs/mbm_local_bytes # echo LclFill > info/L3_MON/counter_configs/mbm_local_bytes/event_filter # echo LclNTWr > info/L3_MON/counter_configs/mbm_local_bytes/event_filter # echo LclSlowFill > info/L3_MON/counter_configs/mbm_local_bytes/event_filter # cat info/L3_MON/counter_configs/mbm_local_bytes/event_filter LclFill LclNTWr LclSlowFill Any "later" work needs to be backward compatible with the first phase. If the first phase starts with a file: /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes ... I do not see how second phase can be backward compatible when that work needs a directory with the same name that contains a file for configuration: /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter sidenote: I think interactions with the "event_filter" file needs more descriptions since it is not clear with the provided example how user space may want to interact with the file when adding vs replacing event configurations. > > My plan was to support only the default configurations in the first phase. > That way there is no difference in the usage model with ABMC when mounted. > > >> >>> >>>> >>>>> >>>>>> >>>>>>>> >>>>>>>> # #cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes >>>>>>>> LclFill, LclNTWr, RmtFill >>>>>>>> >>>>>>>> 3. The default configurations will be used when user mounts the resctrl. >>>>>>>> >>>>>>>> mount -t resctrl resctrl /sys/fs/resctrl/ >>>>>>>> mkdir /sys/fs/resctrl/test/ >>>>>>>> >>>>>>>> 4. The resctrl group/domains can be in one of these assingnment states. >>>>>>>> e: Exclusive >>>>>>>> s: Shared >>>>>>>> u: Unassigned >>>>>>>> >>>>>>>> Exclusive mode is supported now. Shared mode will be supported in the >>>>>>>> future. >>>>>>>> >>>>>>>> 5. We can use the current /sys/fs/resctrl/info/L3_MON/mbm_assign_control >>>>>>>> to list the assignment state of all the groups. >>>>>>>> >>>>>>>> Format: >>>>>>>> "<CTRL_MON group>/<MON group>/<confguration>:<domain_id>=<assign state>" >>>>>>>> >>>>>>>> # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control >>>>>>>> test//mbm_total_bytes:0=e;1=e >>>>>>>> test//mbm_local_bytes:0=e;1=e >>>>>>>> //mbm_total_bytes:0=e;1=e >>>>>>>> //mbm_local_bytes:0=e;1=e >>>> >>>> This would make mbm_assign_control even more unwieldy and quicker to exceed a >>>> page of data (these examples never seem to reflect those AMD systems with the many >>>> L3 domains). How to handle resctrl files larger than 4KB needs to be well understood >>>> and solved when/if going this route. >>> >>> This problem is not specific this series. I feel it is a generic problem >>> to many of the semilar interfaces. I dont know how it is addressed. May >>> have to investigate on this. Any pointers would be helpful. >> >> Dave Martin already did a lot of analysis here. What other pointers do you need? >> >>> >>> >>>> >>>> There seems to be two opinions about this file at moment. Would it be possible to >>>> summarize the discussion with pros/cons raised to make an informed selection? >>>> I understand that Google as represented by Peter no longer requires/requests this >>>> file but the motivation for this change seems new and does not seem to reduce the >>>> original motivation for this file. We may also want to separate requirements for reading >>>> from and writing to this file. >>> >>> Yea. We can just use mbm_assign_control for reading the assignment states. >>> >>> Summary: We have two proposals. >>> >>> First one from Peter: >>> >>> https://lore.kernel.org/lkml/CALPaoCiii0vXOF06mfV=kVLBzhfNo0SFqt4kQGwGSGVUqvr2Dg@xxxxxxxxxxxxxx/ >>> >>> >>> Pros >>> a. Allows flexible creation of free-form names for assignable >>> configurations, stored in info/L3_MON/counter_configs/. >>> >>> b. Events can be accessed using corresponding free-form names in the >>> mon_data directory, making it clear to users what each event represents. >>> >>> >>> Cons: >>> a. Requires three separate files for assignment in each group >>> (assign_exclusive, assign_shared, unassign), which might be excessive. >>> >>> b. No built-in listing support, meaning users must query each group >>> individually to check assignment states. >>> >>> >>> Second Proposal (Mine) >>> >>> https://lore.kernel.org/lkml/a4ab53b5-03be-4299-8853-e86270d46f2e@xxxxxxx/ >>> >>> Pros: >>> >>> a. Maintains the flexibility of free-form names for assignable >>> configurations (info/L3_MON/counter_configs/). >>> >>> b. Events remain accessible via free-form names in mon_data, ensuring >>> clarity on their purpose. >>> >>> c. Adds the ability to list assignment states for all groups in a single >>> command. >>> >>> Cons: >>> a. Potential buffer overflow issues when handling a large number of >>> groups and domains and code complexity to fix the issue. >>> >>> >>> Third Option: A Hybrid Approach >>> >>> We could combine elements from both proposals: >>> >>> a. Retain the free-form naming approach for assignable configurations in >>> info/L3_MON/counter_configs/. >>> >>> b. Use the assignment method from the first proposal: >>> $mkdir test >>> $echo mbm_local_bytes > test/mon_data/mon_L3_00/assign_exclusive >>> >>> c. Introduce listing support via the info/L3_MON/mbm_assign_control >>> interface, enabling users to read assignment states for all groups in one >>> place. Only reading support. >>> >>> >>>> >>>>>>>> >>>>>>>> 6. Users can modify the assignment state by writing to mbm_assign_control. >>>>>>>> >>>>>>>> Format: >>>>>>>> “<CTRL_MON group>/<MON group>/<configuration>:<domain_id>=<assign state>” >>>>>>>> >>>>>>>> #echo "test//mbm_local_bytes:0=e;1=e" > >>>>>>>> /sys/fs/resctrl/info/L3_MON/mbm_assign_control >>>>>>>> >>>>>>>> #echo "test//mbm_local_bytes:0=u;1=u" > >>>>>>>> /sys/fs/resctrl/info/L3_MON/mbm_assign_control >>>>>>>> >>>>>>>> # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_control >>>>>>>> test//mbm_total_bytes:0=u;1=u >>>>>>>> test//mbm_local_bytes:0=u;1=u >>>>>>>> //mbm_total_bytes:0=e;1=e >>>>>>>> //mbm_local_bytes:0=e;1=e >>>>>>>> >>>>>>>> The corresponding events will be read in >>>>>>>> >>>>>>>> /sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_bytes >>>>>>>> /sys/fs/resctrl/mon_data/mon_L3_01/mbm_total_bytes >>>>>>>> /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes >>>>>>>> /sys/fs/resctrl/mon_data/mon_L3_01/mbm_local_bytes >>>>>>>> /sys/fs/resctrl/test/mon_data/mon_L3_00/mbm_total_bytes >>>>>>>> /sys/fs/resctrl/test/mon_data/mon_L3_01/mbm_total_bytes >>>>>>>> /sys/fs/resctrl/test/mon_data/mon_L3_00/mbm_local_bytes >>>>>>>> /sys/fs/resctrl/test/mon_data/mon_L3_01/mbm_local_bytes >>>>>>>> >>>>>>>> 7. In the first stage, only two configurations(mbm_total_bytes and >>>>>>>> mbm_local_bytes) will be supported. >>>>>>>> >>>>>>>> 8. In the future, there will be options to create multiple configurations >>>>>>>> and corresponding directory will be created in >>>>>>>> /sysf/fs/resctrl/test/mon_data/mon_L3_00/<configation name>. >>>>>> >>>>>> Would this be done by creating a new file in the /sys/fs/resctrl/info/L3_MON/counter_configs >>>>>> directory? Like this: >>>>>> >>>>>> # echo "LclFill, LclNTWr, RmtFill" > >>>>>> /sys/fs/resctrl/info/L3_MON/counter_configs/cache_stuff >>>>>> >>>>>> This seems OK (dependent on the user picking meaningful names for >>>>>> the set of attributes picked ... but if they want to name this >>>>>> monitor file "brian" then they have to live with any confusion >>>>>> that they bring on themselves). >>>>>> >>>>>> Would this involve an extension to kernfs? I don't see a function >>>>>> pointer callback for file creation in kernfs_syscall_ops. >>>>>> >>>>>>>> >>>>>>> >>>>>>> I know you are all busy with multiple series going on parallel. I am still >>>>>>> waiting for the inputs on this. It will be great if you can spend some time >>>>>>> on this to see if we can find common ground on the interface. >>>>>>> >>>>>>> Thanks >>>>>>> Babu >>>>>> >>>>>> -Tony >>>>>> >>>>> >>>>> >>>>> thanks >>>>> Babu >>>> >>>> Reinette >>>> >>>> >>> >> >> >
