[SPDK] Re: iSCSI Sequential Read with BS 128K Performance

[Lego Lin <lego.lin at gmail.com>]

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Hi, all:

Sorry for previous email that miss 1 thing: I test performance with SPDK
NULL Block Device

On Fri, Dec 18, 2020 at 4:09 PM Lego Lin <lego.lin(a)gmail.com> wrote:

> Hi, all:
> I just tested SPDK 20.10.x iSCSI performance and I got
> following performance data: (All Testing with FIO QD 32)
> [OK] (100%RndR_4K,   100%RndW_4K)   : (read: IOPS=155k, BW=605MiB/s
> (634MB/s),   write: IOPS=140k, BW=547MiB/s (573MB/s))
> [OK] (100%RndR_8K,   100%RndW_8K)   : (read: IOPS=147k, BW=1152MiB/s
> (1208MB/s), write: IOPS=128k, BW=1003MiB/s (1051MB/s))
> [NOK] (100%SeqR_128K, 100%SeqW_128K) : (read: IOPS=210, BW=26.3MiB/s
> (27.5MB/s),  write: IOPS=14.6k, BW=1831MiB/s (1920MB/s))
> => Read Bad, Write OK
> [NOK] (100%SeqR_32K,  100%SeqR_16K)  : (read: IOPS=9418, BW=294MiB/s
> (309MB/s),   read: IOPS=105k, BW=1641MiB/s (1721MB/s))
> => [NOK] BS_32K + QD_32
> => [OK]  BS_16K + QD_32
> [OK] (100%SeqR_8K,   100%SeqR_4K)   : (read: IOPS=149k, BW=1160MiB/s
> (1217MB/s), read: IOPS=157k, BW=612MiB/s (642MB/s))
>
> Focus on BS 128K
> [OK] QD1: read: IOPS=5543, BW=693MiB/s (727MB/s)
> [OK] QD8: read: IOPS=21.1k, BW=2634MiB/s (2762MB/s)
> [NOK] QD16: read: IOPS=301, BW=37.7MiB/s (39.5MB/s)
>
> FIO Configuration:
> ioengine=libaio
> direct=1
> numjobs=1
>
> I also check with document:
> https://ci.spdk.io/download/performance-reports/SPDK_tcp_perf_report_2007.pdf
> Inside this document, it also suggest Sequential Read test with BS=128K +
> QD8
>
> I think the low performance with BS=128K + QD32 should not relate to
> iSCSI, but can anyone share experience about tuning iSCSI sequential read
> performance? It's weird that performance drop with high QD. Any suggestion
> are welcome.
>
> Thanks
>
> Following are my test configuration
> 1. Network bandwidth: 40GB
> 2. TCP Setting at both target and client
>     tcp_timestamps: "1"
>     tcp_sack: "0",
>     tcp_rmem: "4096 87380 134217728"
>     tcp_wmem: "4096 87380 134217728",
>     tcp_mem: "4096 87380 134217728",
>     rmem_default: "524287",
>     wmem_default: "524287",
>     rmem_max: "268435456",
>     wmem_max: "268435456",
>     optmem_max: "268435456",
>     netdev_max_backlog: "300000"}
> 3. number of CPU cores at target and client: 48 vcores
>      Intel(R) Xeon(R) Silver 4215 CPU @ 2.50GHz * 2
> 4. disable irqbalance / enable CPU power government
> 5. run SPDK with: ./iscsi_tgt -m 0x08007C08007C
>