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

[Yang, Ziye <ziye.yang at intel.com>]

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Hi Lego Lin,

When you use RPC to set the iscsi subsystem status,  
iscsi_set_options, could you use 
'-x' or  '--max-large-datain-per-connection'  to enlarge the datain per connection value. The default value is 64. 

The use of iscsi_set_options can be viewed from ./test/iscsi_tgt/ext4test/ext4test.sh as an example.  If you do not want to use RPC, you can use a json format.  

I believe this value can affect the performance  of iSCSI target with large IO_SIZE + large QD.

Thanks.




Best Regards,
Ziye Yang

-----Original Message-----
From: Lego Lin <lego.lin(a)gmail.com> 
Sent: Wednesday, December 23, 2020 10:19 PM
To: Storage Performance Development Kit <spdk(a)lists.01.org>
Subject: [SPDK] Re: iSCSI Sequential Read with BS 128K Performance

Hi, Ziye:

I modify the buffer size as following:
//#define BUF_SMALL_POOL_SIZE                   8191
#define BUF_SMALL_POOL_SIZE                   16381
//#define BUF_LARGE_POOL_SIZE                   1023
#define BUF_LARGE_POOL_SIZE                   4095

But still got bad performance with SeqRead BS=128K + QD=32 on SPDK NULL Block Device.

Any other suggestions?

Thanks


On Wed, Dec 23, 2020 at 10:16 AM Yang, Ziye <ziye.yang(a)intel.com> wrote:

> Hi Lego,
>
> If you want to test, but not changing the code, you may try  the 
> following
> patch:
>
> https://review.spdk.io/gerrit/c/spdk/spdk/+/5664 It supports to 
> leverage RPC to configure the small and large buffer pool size.
>
>
>
>
> Best Regards,
> Ziye Yang
>
> -----Original Message-----
> From: Yang, Ziye
> Sent: Tuesday, December 22, 2020 1:46 PM
> To: Storage Performance Development Kit <spdk(a)lists.01.org>
> Subject: RE: [SPDK] iSCSI Sequential Read with BS 128K Performance
>
> Hi Lego,
>
> " 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) "
>
> How about changing
>
> #define BUF_LARGE_POOL_SIZE                     1023   in lib/bdev/bdev.c
>
> This Macro may have impact on the performance if you testing big I/O 
> size test. We currently define 1023 * 64 KB with the total size.  So 
> Would you change the value to a bigger value, and see whether it helps 
> the test? // Currently, we did not export it to configurable yet.
>
>
> Best Regards,
> Ziye Yang
>
> -----Original Message-----
> From: Lego Lin <lego.lin(a)gmail.com>
> Sent: Friday, December 18, 2020 4:09 PM
> To: Storage Performance Development Kit <spdk(a)lists.01.org>
> Subject: [SPDK] iSCSI Sequential Read with BS 128K Performance
>
> 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_2
> 007.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 _______________________________________________
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