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From: Kent Overstreet <>
Cc: Kent Overstreet <>
Subject: [PATCH 0/2] generic_file_buffered_read improvements
Date: Wed, 15 Aug 2018 19:26:30 -0400	[thread overview]
Message-ID: <> (raw)

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).

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(-)


             reply	other threads:[~2018-08-16  2:21 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-15 23:26 Kent Overstreet [this message]
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 ` [PATCH 0/2] generic_file_buffered_read improvements Carlos Maiolino
2018-08-16 10:05   ` Kent Overstreet
2018-08-17 22:42     ` Dave Chinner

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