From: Sumit Saxena <sumit.saxena@broadcom.com>
To: John Garry <john.garry@huawei.com>
Cc: Hannes Reinecke <hare@suse.de>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
James Bottomley <james.bottomley@hansenpartnership.com>,
Ming Lei <ming.lei@redhat.com>,
Linux SCSI List <linux-scsi@vger.kernel.org>,
linux-block@vger.kernel.org, Hannes Reinecke <hare@suse.com>
Subject: Re: [PATCH 09/11] megaraid_sas: switch fusion adapters to MQ
Date: Fri, 17 Jan 2020 16:48:34 +0530 [thread overview]
Message-ID: <CAL2rwxpLY1xfbiW4CZ6nWF7W8_zLWS+a+W6XC6emcVm96XetNw@mail.gmail.com> (raw)
In-Reply-To: <11034edd-732a-3dd5-0bdc-891b9de05e56@huawei.com>
On Mon, Jan 13, 2020 at 11:12 PM John Garry <john.garry@huawei.com> wrote:
>
> On 10/01/2020 04:00, Sumit Saxena wrote:
> > On Mon, Dec 9, 2019 at 4:32 PM Hannes Reinecke <hare@suse.de> wrote:
> >>
> >> On 12/9/19 11:10 AM, Sumit Saxena wrote:
> >>> On Mon, Dec 2, 2019 at 9:09 PM Hannes Reinecke <hare@suse.de> 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
next prev parent reply other threads:[~2020-01-17 11:19 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-02 15:39 [PATCH RFC v5 00/11] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs Hannes Reinecke
2019-12-02 15:39 ` [PATCH 01/11] blk-mq: Remove some unused function arguments Hannes Reinecke
2019-12-02 15:39 ` [PATCH 02/11] blk-mq: rename BLK_MQ_F_TAG_SHARED as BLK_MQ_F_TAG_QUEUE_SHARED Hannes Reinecke
2019-12-02 15:39 ` [PATCH 03/11] blk-mq: rename blk_mq_update_tag_set_depth() Hannes Reinecke
2019-12-03 14:30 ` John Garry
2019-12-03 14:53 ` Hannes Reinecke
2019-12-02 15:39 ` [PATCH 04/11] blk-mq: Facilitate a shared sbitmap per tagset Hannes Reinecke
2019-12-03 14:54 ` John Garry
2019-12-03 15:02 ` Hannes Reinecke
2019-12-04 10:24 ` John Garry
2019-12-03 16:38 ` Bart Van Assche
2019-12-02 15:39 ` [PATCH 05/11] blk-mq: add WARN_ON in blk_mq_free_rqs() Hannes Reinecke
2019-12-02 15:39 ` [PATCH 06/11] blk-mq: move shared sbitmap into elevator queue Hannes Reinecke
2019-12-02 15:39 ` [PATCH 07/11] scsi: Add template flag 'host_tagset' Hannes Reinecke
2019-12-02 15:39 ` [PATCH 08/11] scsi: hisi_sas: Switch v3 hw to MQ Hannes Reinecke
2019-12-02 15:39 ` [PATCH 09/11] megaraid_sas: switch fusion adapters " Hannes Reinecke
2019-12-09 10:10 ` Sumit Saxena
2019-12-09 11:02 ` Hannes Reinecke
2020-01-10 4:00 ` Sumit Saxena
2020-01-10 12:18 ` John Garry
2020-01-13 17:42 ` John Garry
2020-01-14 7:05 ` Hannes Reinecke
2020-01-16 15:47 ` John Garry
2020-01-16 17:45 ` Hannes Reinecke
2020-01-17 11:40 ` Sumit Saxena
2020-01-17 11:18 ` Sumit Saxena [this message]
2020-02-13 10:07 ` John Garry
2020-02-17 10:09 ` Sumit Saxena
2020-01-09 11:55 ` John Garry
2020-01-09 15:19 ` Hannes Reinecke
2020-01-09 18:17 ` John Garry
2020-01-10 2:00 ` Ming Lei
2020-01-10 12:09 ` John Garry
2020-01-14 13:57 ` John Garry
2019-12-02 15:39 ` [PATCH 10/11] smartpqi: enable host tagset Hannes Reinecke
2019-12-02 15:39 ` [PATCH 11/11] hpsa: enable host_tagset and switch to MQ Hannes Reinecke
2020-02-26 11:09 ` [PATCH RFC v5 00/11] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs John Garry
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