linux-kernel - Re: [PATCH] uio: Replace mutex info_lock with percpu

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Date:   Tue, 17 May 2022 09:33:07 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Guixin Liu <kanie@...ux.alibaba.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] uio: Replace mutex info_lock with percpu_ref

On Tue, May 10, 2022 at 01:50:31PM +0800, Guixin Liu wrote:
> If the underlying driver works in parallel, the mutex info_lock in uio 
> will force driver to work sequentially, so that become performance 
> bottleneck. Lets replace it with percpu_ref for better performance. 
> 
> Use tcm_loop and tcmu(backstore is file, and I did some work to make tcmu
> work in parallel at uio_write() path) to evaluate performance,
> fio job: fio -filename=/dev/sdb  -direct=1 -size=2G -name=1 -thread
> -runtime=60 -time_based  -rw=randread -numjobs=16 -iodepth=16 -bs=128k
> 
> Without this patch:
> 	READ: bw=2828MiB/s (2965MB/s), 176MiB/s-177MiB/s (185MB/s-186MB/s), 
> io=166GiB (178GB), run=60000-60001msec
> 
> With this patch:
> 	READ: bw=3382MiB/s (3546MB/s), 211MiB/s-212MiB/s (221MB/s-222MB/s), 
> io=198GiB (213GB), run=60001-60001msec
> 
> Reviewed-by: Xiaoguang Wang <xiaoguang.wang@...ux.alibaba.com>

Any reason why you didn't cc: this person on the patch submission so
that they would be part of the conversation about it?

thanks,

greg k-h