Fri, Jan 12, 2024 at 09:29:35AM CET, guwen@xxxxxxxxxxxxxxxxx wrote: > > >On 2024/1/11 22:50, Jiri Pirko wrote: >> Thu, Jan 11, 2024 at 01:00:21PM CET, guwen@xxxxxxxxxxxxxxxxx wrote: >> > This patch set acts as the second part of the new version of [1] (The first >> > part can be referred from [2]), the updated things of this version are listed >> > at the end. >> > >> > # Background >> > >> > SMC-D is now used in IBM z with ISM function to optimize network interconnect >> > for intra-CPC communications. Inspired by this, we try to make SMC-D available >> >> Care to provide more details about what ISM and intra-CPC is and what it >> it good for? >> > >Hi Jiri, > >Sure, > >ISM (IBM System Z Internal Shared Memory) is a technology that provides the >internal communications capability required for SMC-D. It is a virtual PCI >network adapter that enables direct access to shared virtual memory providing >a highly optimized network interconnect for IBM Z intra-CPC communications. >(It can be found in https://www.ibm.com/docs/en/zos/3.1.0?topic=communications-shared-memory-reference-information >and https://www.ibm.com/docs/en/zos/3.1.0?topic=dv2-ismv2) > >CPC (Central processor complex) is an IBM mainframe term to refer to the physical >collection of hardware that includes main storage, one or more central processors, >timers, and channels. >(It can be found in https://www.ibm.com/docs/en/zos-basic-skills?topic=concepts-mainframe-hardware-terminology >and https://www.ibm.com/docs/en/ztpf/2023?topic=support-central-processor-complex-cpc) > >SMC (Shared Memory Communications) is a network protocol that allows two SMC >capable peers to communicate using memory that each peer allocates and manages >for their partner’s use. It has two forms: > >- SMC over Remote Direct Memory Access (SMC-R) > > It is an open protocol that was initially introduced in z/OS V2R1 on the IBM zEC12. > SMC-R is defined in an informational RFC entitled IBM’s Shared Memory Communications > over RDMA (https://tools.ietf.org/html/rfc7609). > >- SMC - Direct Memory Access (SMC-D) > > It is a variation of SMC-R. SMC-D is closely related to SMC-R but is based on the > Internal Shared Memory (ISM) capabilities introduced with the IBM z13™ (z13) hardware > model. > >(SMC protocol can be found in https://www.ibm.com/support/pages/system/files/inline-files/IBM%20Shared%20Memory%20Communications%20Version%202.1_0.pdf) > >So with ISM function, SMC-D can be used to improves throughput, lowers latency and cost, >and maintains existing functions of communications within CPC. > >> >> > on the non-s390 architecture through a software-implemented virtual ISM device, >> > that is the loopback-ism device here, to accelerate inter-process or >> >> I see no such device. Is it a netdevice? > >Currently, SMC-D depends on ISM and is only available on IBM Z systems. Now we try >to make SMC-D available on other system architectures other than s390 and Z system. >So 'virtual ISM' is proposed and acts as original firmware ISM on Z system. >(The virtual ISM supports can be found in https://lore.kernel.org/netdev/20231219142616.80697-1-guwen@xxxxxxxxxxxxxxxxx/) > >The loopback-ism is the first virtual ISM. It does not rely on a specific architecture >or hardware, and provides functions that ISM should have (like a dummy device). It is >designed to be used by SMC-D when communication occurs within OS instance. > >It is not a typical network device, since it primarily provides exact functions >defined by SMC-D device operations(struct smcd_ops), e.g. provides and manages the >shared memory (term used is DMB in SMC, Direct Memory Buffer). > >It can't be found now since it is introduced by this patchset. > >> >> If it is "software-implemented", why is it part of smc driver and not >> separate soft-device driver? If there is some smc specific code, I guess >> there should be some level of separation. Can't this be implemented by >> other devices too? >> > >loopback-ism is designed to specifically used by SMC-D (like s390 ISM), to >serves as a easy-available ISM for community to test SMC-D and to accelerate >intra-OS communication (see benchmark test). So the code is under net/smc. Got it. > >> >> >> > inter-containers communication within the same OS instance. >> > >> > # Design >> > >> > This patch set includes 3 parts: >> > >> > - Patch #1-#2: some prepare work for loopback-ism. >> > - Patch #3-#9: implement loopback-ism device. >> > - Patch #10-#15: memory copy optimization for loopback scenario. >> > >> > The loopback-ism device is designed as a ISMv2 device and not be limited to >> > a specific net namespace, ends of both inter-process connection (1/1' in diagram >> > below) or inter-container connection (2/2' in diagram below) can find the same >> > available loopback-ism and choose it during the CLC handshake. >> > >> > Container 1 (ns1) Container 2 (ns2) >> > +-----------------------------------------+ +-------------------------+ >> > | +-------+ +-------+ +-------+ | | +-------+ | >> > | | App A | | App B | | App C | | | | App D |<-+ | >> > | +-------+ +---^---+ +-------+ | | +-------+ |(2') | >> > | |127.0.0.1 (1')| |192.168.0.11 192.168.0.12| | >> > | (1)| +--------+ | +--------+ |(2) | | +--------+ +--------+ | >> > | `-->| lo |-` | eth0 |<-` | | | lo | | eth0 | | >> > +---------+--|---^-+---+-----|--+---------+ +-+--------+---+-^------+-+ >> > | | | | >> > Kernel | | | | >> > +----+-------v---+-----------v----------------------------------+---+----+ >> > | | TCP | | >> > | | | | >> > | +--------------------------------------------------------------+ | >> > | | >> > | +--------------+ | >> > | | smc loopback | | >> > +---------------------------+--------------+-----------------------------+ >> > >> > loopback-ism device creates DMBs (shared memory) for each connection peer. >> > Since data transfer occurs within the same kernel, the sndbuf of each peer >> > is only a descriptor and point to the same memory region as peer DMB, so that >> > the data copy from sndbuf to peer DMB can be avoided in loopback-ism case. >> > >> > Container 1 (ns1) Container 2 (ns2) >> > +-----------------------------------------+ +-------------------------+ >> > | +-------+ | | +-------+ | >> > | | App C |-----+ | | | App D | | >> > | +-------+ | | | +-^-----+ | >> > | | | | | | >> > | (2) | | | (2') | | >> > | | | | | | >> > +---------------|-------------------------+ +----------|--------------+ >> > | | >> > Kernel | | >> > +---------------|-----------------------------------------|--------------+ >> > | +--------+ +--v-----+ +--------+ +--------+ | >> > | |dmb_desc| |snd_desc| |dmb_desc| |snd_desc| | >> > | +-----|--+ +--|-----+ +-----|--+ +--------+ | >> > | +-----|--+ | +-----|--+ | >> > | | DMB C | +---------------------------------| DMB D | | >> > | +--------+ +--------+ | >> > | | >> > | +--------------+ | >> > | | smc loopback | | >> > +---------------------------+--------------+-----------------------------+ >> > >> > # Benchmark Test >> > >> > * Test environments: >> > - VM with Intel Xeon Platinum 8 core 2.50GHz, 16 GiB mem. >> > - SMC sndbuf/DMB size 1MB. >> > - /sys/devices/virtual/smc/loopback-ism/dmb_copy is set to default 0, >> > which means sndbuf and DMB are merged and no data copied between them. >> > - /sys/devices/virtual/smc/loopback-ism/dmb_type is set to default 0, >> >> Exposing any configuration knobs and statistics over sysfs for >> softdevices does not look correct at all :/ Could you please avoid >> sysfs? >> > >In previous reviews and calls, we think loopback-ism needs to be more >like a device and be visible under /sys/devices. > >Would you mind explaining why using sysfs for loopback-ism is not correct? >since I saw some other configurations or statistics exists under /sys/devices, >e.g. /sys/devices/virtual/net/lo. Thank you! You have smc_netlink.c exposing clear netlink api for the subsystem. Can't you extend it to contain the configuration knobs and expose stats instead of sysfs? > > > >Thanks again, >Wen Gu > >> >> > which means DMB is physically contiguous buffer. >> > >> > * Test object: >> > - TCP: run on TCP loopback. >> > - SMC lo: run on SMC loopback device. >> > >> > 1. ipc-benchmark (see [3]) >> > >> > - ./<foo> -c 1000000 -s 100 >> > >> > TCP SMC-lo >> > Message >> > rate (msg/s) 80636 149515(+85.42%) >> > >> > 2. sockperf >> > >> > - serv: <smc_run> taskset -c <cpu> sockperf sr --tcp >> > - clnt: <smc_run> taskset -c <cpu> sockperf { tp | pp } --tcp --msg-size={ 64000 for tp | 14 for pp } -i 127.0.0.1 -t 30 >> > >> > TCP SMC-lo >> > Bandwidth(MBps) 4909.36 8197.57(+66.98%) >> > Latency(us) 6.098 3.383(-44.52%) >> > >> > 3. nginx/wrk >> > >> > - serv: <smc_run> nginx >> > - clnt: <smc_run> wrk -t 8 -c 1000 -d 30 http://127.0.0.1:80 >> > >> > TCP SMC-lo >> > Requests/s 181685.74 246447.77(+35.65%) >> > >> > 4. redis-benchmark >> > >> > - serv: <smc_run> redis-server >> > - clnt: <smc_run> redis-benchmark -h 127.0.0.1 -q -t set,get -n 400000 -c 200 -d 1024 >> > >> > TCP SMC-lo >> > GET(Requests/s) 85855.34 118553.64(+38.09%) >> > SET(Requests/s) 86824.40 125944.58(+45.06%) >> > >> > >> > Change log: >> > >> > v1->RFC: >> > - Patch #9: merge rx_bytes and tx_bytes as xfer_bytes statistics: >> > /sys/devices/virtual/smc/loopback-ism/xfer_bytes >> > - Patch #10: add support_dmb_nocopy operation to check if SMC-D device supports >> > merging sndbuf with peer DMB. >> > - Patch #13 & #14: introduce loopback-ism device control of DMB memory type and >> > control of whether to merge sndbuf and DMB. They can be respectively set by: >> > /sys/devices/virtual/smc/loopback-ism/dmb_type >> > /sys/devices/virtual/smc/loopback-ism/dmb_copy >> > The motivation for these two control is that a performance bottleneck was >> > found when using vzalloced DMB and sndbuf is merged with DMB, and there are >> > many CPUs and CONFIG_HARDENED_USERCOPY is set [4]. The bottleneck is caused >> > by the lock contention in vmap_area_lock [5] which is involved in memcpy_from_msg() >> > or memcpy_to_msg(). Currently, Uladzislau Rezki is working on mitigating the >> > vmap lock contention [6]. It has significant effects, but using virtual memory >> > still has additional overhead compared to using physical memory. >> > So this new version provides controls of dmb_type and dmb_copy to suit >> > different scenarios. >> > - Some minor changes and comments improvements. >> > >> > RFC->old version([1]): >> > Link: https://lore.kernel.org/netdev/1702214654-32069-1-git-send-email-guwen@xxxxxxxxxxxxxxxxx/ >> > - Patch #1: improve the loopback-ism dump, it shows as follows now: >> > # smcd d >> > FID Type PCI-ID PCHID InUse #LGs PNET-ID >> > 0000 0 loopback-ism ffff No 0 >> > - Patch #3: introduce the smc_ism_set_v2_capable() helper and set >> > smc_ism_v2_capable when ISMv2 or virtual ISM is registered, >> > regardless of whether there is already a device in smcd device list. >> > - Patch #3: loopback-ism will be added into /sys/devices/virtual/smc/loopback-ism/. >> > - Patch #8: introduce the runtime switch /sys/devices/virtual/smc/loopback-ism/active >> > to activate or deactivate the loopback-ism. >> > - Patch #9: introduce the statistics of loopback-ism by >> > /sys/devices/virtual/smc/loopback-ism/{{tx|rx}_tytes|dmbs_cnt}. >> > - Some minor changes and comments improvements. >> > >> > [1] https://lore.kernel.org/netdev/1695568613-125057-1-git-send-email-guwen@xxxxxxxxxxxxxxxxx/ >> > [2] https://lore.kernel.org/netdev/20231219142616.80697-1-guwen@xxxxxxxxxxxxxxxxx/ >> > [3] https://github.com/goldsborough/ipc-bench >> > [4] https://lore.kernel.org/all/3189e342-c38f-6076-b730-19a6efd732a5@xxxxxxxxxxxxxxxxx/ >> > [5] https://lore.kernel.org/all/238e63cd-e0e8-4fbf-852f-bc4d5bc35d5a@xxxxxxxxxxxxxxxxx/ >> > [6] https://lore.kernel.org/all/20240102184633.748113-1-urezki@xxxxxxxxx/ >> > >> > Wen Gu (15): >> > net/smc: improve SMC-D device dump for virtual ISM >> > net/smc: decouple specialized struct from SMC-D DMB registration >> > net/smc: introduce virtual ISM device loopback-ism >> > net/smc: implement ID-related operations of loopback-ism >> > net/smc: implement some unsupported operations of loopback-ism >> > net/smc: implement DMB-related operations of loopback-ism >> > net/smc: register loopback-ism into SMC-D device list >> > net/smc: introduce loopback-ism runtime switch >> > net/smc: introduce loopback-ism statistics attributes >> > net/smc: add operations to merge sndbuf with peer DMB >> > net/smc: attach or detach ghost sndbuf to peer DMB >> > net/smc: adapt cursor update when sndbuf and peer DMB are merged >> > net/smc: introduce loopback-ism DMB type control >> > net/smc: introduce loopback-ism DMB data copy control >> > net/smc: implement DMB-merged operations of loopback-ism >> > >> > drivers/s390/net/ism_drv.c | 2 +- >> > include/net/smc.h | 7 +- >> > net/smc/Kconfig | 13 + >> > net/smc/Makefile | 2 +- >> > net/smc/af_smc.c | 28 +- >> > net/smc/smc_cdc.c | 58 ++- >> > net/smc/smc_cdc.h | 1 + >> > net/smc/smc_core.c | 61 +++- >> > net/smc/smc_core.h | 1 + >> > net/smc/smc_ism.c | 71 +++- >> > net/smc/smc_ism.h | 5 + >> > net/smc/smc_loopback.c | 718 +++++++++++++++++++++++++++++++++++++ >> > net/smc/smc_loopback.h | 88 +++++ >> > 13 files changed, 1026 insertions(+), 29 deletions(-) >> > create mode 100644 net/smc/smc_loopback.c >> > create mode 100644 net/smc/smc_loopback.h >> > >> > -- >> > 2.32.0.3.g01195cf9f >> > >> >
