linux-ext4 - Re: [PATCH v5 2/2] ext4: Make cache hits/misses per-cpu counts

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Date:	Thu, 5 May 2016 16:03:29 +0200
From:	Jan Kara <jack@...e.cz>
To:	Waiman Long <Waiman.Long@....com>
Cc:	Theodore Ts'o <tytso@....edu>,
	Andreas Dilger <adilger.kernel@...ger.ca>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Matthew Wilcox <willy@...ux.intel.com>,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
	Dave Chinner <david@...morbit.com>,
	Christoph Hellwig <hch@...radead.org>,
	Scott J Norton <scott.norton@....com>,
	Douglas Hatch <doug.hatch@....com>,
	Toshimitsu Kani <toshi.kani@....com>
Subject: Re: [PATCH v5 2/2] ext4: Make cache hits/misses per-cpu counts

On Fri 29-04-16 12:27:56, Waiman Long wrote:
> This patch changes the es_stats_cache_hits and es_stats_cache_misses
> statistics counts to percpu counters to reduce cacheline contention
> issues whem multiple threads are trying to update those counts
> simultaneously.
> 
> With a 38-threads fio I/O test with 2 shared files (on DAX-mount
> NVDIMM) running on a 4-socket Haswell-EX server with 4.6-rc1 kernel,
> the aggregated bandwidths before and after the patch were:
> 
>   Test          W/O patch       With patch      % change
>   ----          ---------       ----------      --------
>   Read-only     16499MB/s       17215MB/s        +4.3%
>   Read-write     4361MB/s        4794MB/s        +9.9%
> 
> Signed-off-by: Waiman Long <Waiman.Long@....com>

The patch looks good. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR
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