Re: [f2fs-dev] [PATCH 2/2] f2fs: introduce F2FS_UNFAIR_RWSEM to support unfair rwsem

[Chao Yu]

On 2022/3/4 10:19, Jaegeuk Kim wrote:
> Unfair rwsem should be used when blk-cg is on. Otherwise, there is regression.
>
> FYI, we noticed a -26.7% regression of aim7.jobs-per-min due to commit:
>
> commit: e4544b63a7ee49e7fbebf35ece0a6acd3b9617ae ("f2fs: move f2fs to use reader-unfair rwsems")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> in testcase: aim7
> on test machine: 88 threads 2 sockets Intel(R) Xeon(R) Gold 6238M CPU @ 2.10GHz with 128G memory
> with following parameters:
>
> 	disk: 4BRD_12G
> 	md: RAID0
> 	fs: f2fs
> 	test: sync_disk_rw
> 	load: 100
> 	cpufreq_governor: performance
> 	ucode: 0x500320a
>
> test-description: AIM7 is a traditional UNIX system level benchmark suite which is used to test and measure the performance of multiuser system.
> test-url: https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsourceforge.net%2Fprojects%2Faimbench%2Ffiles%2Faim-suite7%2F&data=04%7C01%7Cchao.yu%40oppo.com%7C22ad61cc1e204e1d63e908d9fd858d65%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637819572336831789%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=SMV5sGpVhSvjC8sbrKpKGT27J35Bm1%2B3KoM4yeraceA%3D&reserved=0
>
> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>

Reviewed-by: Chao Yu <chao@xxxxxxxxxx>

Thanks,