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Date:   Sat, 24 Aug 2019 23:25:24 -0400
From:   "Theodore Y. Ts'o" <tytso@mit.edu>
To:     Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc:     linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
        Yang Guo <guoyang2@huawei.com>,
        Andreas Dilger <adilger.kernel@dilger.ca>
Subject: Re: [PATCH] ext4: change the type of ext4 cache stats to
 percpu_counter to improve performance
Message-ID: <20190825032524.GD5163@mit.edu>
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        Shaokun Zhang <zhangshaokun@hisilicon.com>,
        linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
        Yang Guo <guoyang2@huawei.com>,
        Andreas Dilger <adilger.kernel@dilger.ca>
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On Fri, Aug 23, 2019 at 10:47:34AM +0800, Shaokun Zhang wrote:
> From: Yang Guo <guoyang2@huawei.com>
> 
> @es_stats_cache_hits and @es_stats_cache_misses are accessed frequently in
> ext4_es_lookup_extent function, it would influence the ext4 read/write
> performance in NUMA system.
> Let's optimize it using percpu_counter, it is profitable for the
> performance.
> 
> The test command is as below:
> fio -name=randwrite -numjobs=8 -filename=/mnt/test1 -rw=randwrite
> -ioengine=libaio -direct=1 -iodepth=64 -sync=0 -norandommap -group_reporting
> -runtime=120 -time_based -bs=4k -size=5G
> 
> And the result is better 10% than the initial implement:
> without the patch，IOPS=197k, BW=770MiB/s (808MB/s)(90.3GiB/120002msec)
> with the patch,  IOPS=218k, BW=852MiB/s (894MB/s)(99.9GiB/120002msec)
> 
> Cc: "Theodore Ts'o" <tytso@mit.edu>
> Cc: Andreas Dilger <adilger.kernel@dilger.ca>
> Signed-off-by: Yang Guo <guoyang2@huawei.com>
> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>

Applied with some adjustments so it would apply.  I also changed the patch summary to:

    ext4: use percpu_counters for extent_status cache hits/misses

    	      		      	  		- Ted