On Mon, Jan 13, 2020 at 11:12 PM John Garry <john.garry@xxxxxxxxxx> wrote: > > On 10/01/2020 04:00, Sumit Saxena wrote: > > On Mon, Dec 9, 2019 at 4:32 PM Hannes Reinecke <hare@xxxxxxx> wrote: > >> > >> On 12/9/19 11:10 AM, Sumit Saxena wrote: > >>> On Mon, Dec 2, 2019 at 9:09 PM Hannes Reinecke <hare@xxxxxxx> wrote: > >>>> > >>>> Fusion adapters can steer completions to individual queues, and > >>>> we now have support for shared host-wide tags. > >>>> So we can enable multiqueue support for fusion adapters and > >>>> drop the hand-crafted interrupt affinity settings. > >>> > >>> Hi Hannes, > >>> > >>> Ming Lei also proposed similar changes in megaraid_sas driver some > >>> time back and it had resulted in performance drop- > >>> https://patchwork.kernel.org/patch/10969511/ > >>> > >>> So, we will do some performance tests with this patch and update you. > >>> Thank you. > >> > >> I'm aware of the results of Ming Leis work, but I do hope this patchset > >> performs better. > >> > >> And when you do performance measurements, can you please run with both, > >> 'none' I/O scheduler and 'mq-deadline' I/O scheduler? > >> I've measured quite a performance improvements when using mq-deadline, > >> up to the point where I've gotten on-par performance with the original, > >> non-mq, implementation. > >> (As a data point, on my setup I've measured about 270k IOPS and 1092 > >> MB/s througput, running on just 2 SSDs). > >>asas_build_ldio_fusion > >> But thanks for doing a performance test here. > > > > Hi Hannes, > > > > Sorry for the delay in replying, I observed a few issues with this patchset: > > > > 1. "blk_mq_unique_tag_to_hwq(tag)" does not return MSI-x vector to > > which IO submitter CPU is affined with. Due to this IO submission and > > completion CPUs are different which causes performance drop for low > > latency workloads. > > Hi Sumit, > > So the new code has: > > megasas_build_ldio_fusion() > { > > cmd->request_desc->SCSIIO.MSIxIndex = > blk_mq_unique_tag_to_hwq(tag); > > } > > So the value here is hw queue index from blk-mq point of view, and not > megaraid_sas msix index, as you alluded to. Yes John, value filled in "cmd->request_desc->SCSIIO.MSIxIndex" is HW queue index. > > So we get 80 msix, 8 are reserved for low_latency_index_start (that's > how it seems to me), and we report other 72 as #hw queues = 72 to SCSI > midlayer. > > So I think that this should be: > > cmd->request_desc->SCSIIO.MSIxIndex = > blk_mq_unique_tag_to_hwq(tag) + low_latency_index_start; Agreed, this should return correct HW queue index. > > > > > > lspcu: > > > > # lscpu > > Architecture: x86_64 > > CPU op-mode(s): 32-bit, 64-bit > > Byte Order: Little Endian > > CPU(s): 72 > > On-line CPU(s) list: 0-71 > > Thread(s) per core: 2 > > Core(s) per socket: 18 > > Socket(s): 2 > > NUMA node(s): 2 > > Vendor ID: GenuineIntel > > CPU family: 6 > > Model: 85 > > Model name: Intel(R) Xeon(R) Gold 6150 CPU @ 2.70GHz > > Stepping: 4 > > CPU MHz: 3204.246 > > CPU max MHz: 3700.0000 > > CPU min MHz: 1200.0000 > > BogoMIPS: 5400.00 > > Virtualization: VT-x > > L1d cache: 32K > > L1i cache: 32K > > L2 cache: 1024K > > L3 cache: 25344K > > NUMA node0 CPU(s): 0-17,36-53 > > NUMA node1 CPU(s): 18-35,54-71 > > Flags: fpu vme de pse tsc msr pae mce cx8 apic sep > > mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht > > tm pbe s > > yscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts > > rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq > > dtes64 monitor > > ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 > > sse4_2 x2apic movbe popcnt tsc_deadline_timer xsave avx f16c rdrand > > lahf_lm abm > > 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single intel_ppin > > mba tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust > > bmi1 hle > > avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed > > adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt > > xsavec > > xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_lo > > > > > > [snip] > > > 4. This patch removes below code from driver so what this piece of > > code does is broken- > > > > > > - if (instance->adapter_type >= INVADER_SERIES && > > - !instance->msix_combined) { > > - instance->msix_load_balance = true; > > - instance->smp_affinity_enable = false; > > - } > > Does this code need to be re-added? Would this have affected your test? This code did not affect my test but has to be re-added for affected hardware. There are few megaraid_sas adapters for which "instance->msix_combined" would be "0" and we need this code for those adapters. Thanks, Sumit > > Thanks, > John
