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From: Carlos Maiolino <>
To: Kent Overstreet <>
Subject: Re: [PATCH 0/2] generic_file_buffered_read improvements
Date: Thu, 16 Aug 2018 09:57:40 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, Aug 15, 2018 at 07:26:30PM -0400, Kent Overstreet wrote:
> Small patch series to
>  - firstly, refactor generic_file_buffered_read enough that it can be modified
>    in more interesting ways without going insane, and then
>  - secondly, change it to use find_get_pages_contig() to batch up the page
>    operations, and then copy data to userspace in a separate loop that touches
>    no other shared cachelines.
> I've been seeing profiles where the radix tree lookups in the buffered read path
> are a shockingly large portion of the profile (around 25%, if memory serves) -
> that's what this patch series is addressing. I've benchmarked small block reads
> as well, performance there is unaffected or slightly improved (it's within the
> margin of error).

/me didn't review the patches, but...

Could you share how you benchmarked it? Despite the fact I'm curious about it,
it's going to be interesting the 'proof' of such improvement.


> And as a bonus, the code that was all in generic_file_buffered_read() is now
> _drastically_ easier to follow and modify. I haven't done as much refactoring as
> I could have, I kept as much of the structure of the old code as I could just to
> make things easier on myself, but I'm still pretty happy with the result.
> Kent Overstreet (2):
>   fs: Break generic_file_buffered_read up into multiple functions
>   fs: generic_file_buffered_read() now uses find_get_pages_contig
>  mm/filemap.c | 486 +++++++++++++++++++++++++++++----------------------
>  1 file changed, 273 insertions(+), 213 deletions(-)
> -- 
> 2.18.0


  parent reply	other threads:[~2018-08-16 10:54 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-15 23:26 [PATCH 0/2] generic_file_buffered_read improvements Kent Overstreet
2018-08-15 23:26 ` [PATCH 1/2] fs: Break generic_file_buffered_read up into multiple functions Kent Overstreet
2018-08-15 23:26 ` [PATCH 2/2] fs: generic_file_buffered_read() now uses find_get_pages_contig Kent Overstreet
2018-08-16 14:56   ` kbuild test robot
2018-08-16  7:57 ` Carlos Maiolino [this message]
2018-08-16 10:05   ` [PATCH 0/2] generic_file_buffered_read improvements Kent Overstreet
2018-08-17 22:42     ` Dave Chinner

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