Re: [PATCH RFC 09/13] x86/irq: Install posted MSI notification handler

From: Jacob Pan
Date: Fri Jan 26 2024 - 18:28:27 EST

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Hi Thomas,

On Fri, 08 Dec 2023 12:52:49 +0100, Thomas Gleixner <tglx@xxxxxxxxxxxxx>
wrote:

> > Without PIR copy:
> >
> > DMA memfill bandwidth: 4.944 Gbps
> > Performance counter stats for './run_intr.sh 512 30':
> >
> > 77,313,298,506 L1-dcache-loads
> > (79.98%) 8,279,458 L1-dcache-load-misses #
> > 0.01% of all L1-dcache accesses (80.03%) 41,654,221,245
> > L1-dcache-stores (80.01%)
> > 10,476 LLC-load-misses # 0.31% of all LL-cache
> > accesses (79.99%) 3,332,748 LLC-loads
> > (80.00%) 30.212055434 seconds time elapsed
> >
> > 0.002149000 seconds user
> > 30.183292000 seconds sys
> >
> >
> > With PIR copy:
> > DMA memfill bandwidth: 5.029 Gbps
> > Performance counter stats for './run_intr.sh 512 30':
> >
> > 78,327,247,423 L1-dcache-loads
> > (80.01%) 7,762,311 L1-dcache-load-misses #
> > 0.01% of all L1-dcache accesses (80.01%) 42,203,221,466
> > L1-dcache-stores (79.99%)
> > 23,691 LLC-load-misses # 0.67% of all LL-cache
> > accesses (80.01%) 3,561,890 LLC-loads
> > (80.00%)
> >
> > 30.201065706 seconds time elapsed
> >
> > 0.005950000 seconds user
> > 30.167885000 seconds sys
>
> Interesting, though I'm not really convinced that this DMA memfill
> microbenchmark resembles real work loads.
>
> Did you test with something realistic, e.g. storage or networking, too?
I have done the following FIO test on NVME drives and not seeing any
meaningful differences in IOPS between the two implementations.

Here is my setup and results on 4 NVME drives connected to a x16 PCIe slot:

+-[0000:62]-
| +-01.0-[63]----00.0 Samsung Electronics Co Ltd NVMe SSD Controller PM174X
| +-03.0-[64]----00.0 Samsung Electronics Co Ltd NVMe SSD Controller PM174X
| +-05.0-[65]----00.0 Samsung Electronics Co Ltd NVMe SSD Controller PM174X
| \-07.0-[66]----00.0 Samsung Electronics Co Ltd NVMe SSD Controller PM174X

libaio, no PIR_COPY
======================================
fio-3.35
Starting 512 processes
Jobs: 512 (f=512): [r(512)][100.0%][r=32.2GiB/s][r=8445k IOPS][eta 00m:00s]
disk_nvme6n1_thread_1: (groupid=0, jobs=512): err= 0: pid=31559: Mon Jan 8 21:49:22 2024
read: IOPS=8419k, BW=32.1GiB/s (34.5GB/s)(964GiB/30006msec)
slat (nsec): min=1325, max=115807k, avg=42368.34, stdev=1517031.57
clat (usec): min=2, max=499085, avg=15139.97, stdev=25682.25
lat (usec): min=68, max=499089, avg=15182.33, stdev=25709.81
clat percentiles (usec):
| 1.00th=[ 734], 5.00th=[ 783], 10.00th=[ 816], 20.00th=[ 857],
| 30.00th=[ 906], 40.00th=[ 971], 50.00th=[ 1074], 60.00th=[ 1369],
| 70.00th=[ 13042], 80.00th=[ 19792], 90.00th=[ 76022], 95.00th=[ 76022],
| 99.00th=[ 77071], 99.50th=[ 81265], 99.90th=[ 85459], 99.95th=[ 91751],
| 99.99th=[200279]
bw ( MiB/s): min=18109, max=51859, per=100.00%, avg=32965.98, stdev=16.88, samples=14839
iops : min=4633413, max=13281470, avg=8439278.47, stdev=4324.70, samples=14839
lat (usec) : 4=0.01%, 10=0.01%, 20=0.01%, 50=0.01%, 100=0.01%
lat (usec) : 250=0.01%, 500=0.01%, 750=1.84%, 1000=41.96%
lat (msec) : 2=18.37%, 4=0.20%, 10=3.88%, 20=13.95%, 50=5.42%
lat (msec) : 100=14.33%, 250=0.02%, 500=0.01%
cpu : usr=1.16%, sys=3.54%, ctx=4932752, majf=0, minf=192764
IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.1%
issued rwts: total=252616589,0,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=256

Run status group 0 (all jobs):
READ: bw=32.1GiB/s (34.5GB/s), 32.1GiB/s-32.1GiB/s (34.5GB/s-34.5GB/s), io=964GiB (1035GB), run=30006-30006msec

Disk stats (read/write):
nvme6n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=96.31%
nvme5n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=97.15%
nvme4n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=98.06%
nvme3n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=98.94%

Performance counter stats for 'system wide':

22,985,903,515 L1-dcache-load-misses (42.86%)
22,989,992,126 L1-dcache-load-misses (57.14%)
751,228,710,993 L1-dcache-stores (57.14%)
465,033,820 LLC-load-misses # 18.27% of all LL-cache accesses (57.15%)
2,545,570,669 LLC-loads (57.14%)
1,058,582,881 LLC-stores (28.57%)
326,135,823 LLC-store-misses (28.57%)

32.045718194 seconds time elapsed
-------------------------------------------
libaio with PIR_COPY
-------------------------------------------
fio-3.35
Starting 512 processes
Jobs: 512 (f=512): [r(512)][100.0%][r=32.2GiB/s][r=8445k IOPS][eta 00m:00s]
disk_nvme6n1_thread_1: (groupid=0, jobs=512): err= 0: pid=5103: Mon Jan 8 23:12:12 2024
read: IOPS=8420k, BW=32.1GiB/s (34.5GB/s)(964GiB/30011msec)
slat (nsec): min=1339, max=97021k, avg=42447.84, stdev=1442726.09
clat (usec): min=2, max=369410, avg=14820.01, stdev=24112.59
lat (usec): min=69, max=369412, avg=14862.46, stdev=24139.33
clat percentiles (usec):
| 1.00th=[ 717], 5.00th=[ 783], 10.00th=[ 824], 20.00th=[ 873],
| 30.00th=[ 930], 40.00th=[ 1012], 50.00th=[ 1172], 60.00th=[ 8094],
| 70.00th=[ 14222], 80.00th=[ 18744], 90.00th=[ 76022], 95.00th=[ 76022],
| 99.00th=[ 76022], 99.50th=[ 78119], 99.90th=[ 81265], 99.95th=[ 81265],
| 99.99th=[135267]
bw ( MiB/s): min=19552, max=62819, per=100.00%, avg=33774.56, stdev=31.02, samples=14540
iops : min=5005807, max=16089892, avg=8646500.17, stdev=7944.42, samples=14540
lat (usec) : 4=0.01%, 10=0.01%, 20=0.01%, 50=0.01%, 100=0.01%
lat (usec) : 250=0.01%, 500=0.01%, 750=2.50%, 1000=36.41%
lat (msec) : 2=17.39%, 4=0.27%, 10=5.83%, 20=18.94%, 50=5.59%
lat (msec) : 100=13.06%, 250=0.01%, 500=0.01%
cpu : usr=1.20%, sys=3.74%, ctx=6758326, majf=0, minf=193128
IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.1%
issued rwts: total=252677827,0,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=256

Run status group 0 (all jobs):
READ: bw=32.1GiB/s (34.5GB/s), 32.1GiB/s-32.1GiB/s (34.5GB/s-34.5GB/s), io=964GiB (1035GB), run=30011-30011msec

Disk stats (read/write):
nvme6n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=96.36%
nvme5n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=97.18%
nvme4n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=98.08%
nvme3n1: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=98.96%

Performance counter stats for 'system wide':

24,762,800,042 L1-dcache-load-misses (42.86%)
24,764,415,765 L1-dcache-load-misses (57.14%)
756,096,467,595 L1-dcache-stores (57.14%)
483,611,270 LLC-load-misses # 16.21% of all LL-cache accesses (57.14%)
2,982,610,898 LLC-loads (57.14%)
1,283,077,818 LLC-stores (28.57%)
313,253,711 LLC-store-misses (28.57%)

32.059810215 seconds time elapsed

Thanks,

Jacob

Next message: Zach O'Keefe: "Re: [PATCH v2 1/1] mm/madvise: add MADV_F_COLLAPSE_LIGHT to process_madvise()"
Previous message: Jacob Pan: "Re: [PATCH RFC 11/13] iommu/vt-d: Add an irq_chip for posted MSIs"
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