Btrfs: Fix streaming read performance with checksumming on

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Large streaming reads make for large bios, which means each entry on the
list async work queues represents a large amount of data.  IO
congestion throttling on the device was kicking in before the async
worker threads decided a single thread was busy and needed some help.

The end result was that a streaming read would result in a single CPU
running at 100% instead of balancing the work off to other CPUs.

This patch also changes the pre-IO checksum lookup done by reads to
work on a per-bio basis instead of a per-page.  This results in many
extra btree lookups on large streaming reads.  Doing the checksum lookup
right before bio submit allows us to reuse searches while processing
adjacent offsets.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

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This commit is contained in:

Chris Mason 2008-07-31 15:42:53 -04:00

parent 37d1aeee39

commit 61b4944018

5 changed files with 99 additions and 54 deletions

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2

fs/btrfs/async-thread.c

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2

fs/btrfs/ctree.h

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15

fs/btrfs/disk-io.c

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77

fs/btrfs/file-item.c

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57

fs/btrfs/inode.c

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