btrfs: create read policy framework

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As of now, we use the pid method to read striped mirrored data, which
means process id determines the stripe id to read. This type of routing
typically helps in a system with many small independent processes tying
to read random data. On the other hand, the pid based read IO policy is
inefficient because if there is a single process trying to read a large
file, the overall disk bandwidth remains underutilized.

So this patch introduces a read policy framework so that we could add
more read policies, such as IO routing based on the device's wait-queue
or manual when we have a read-preferred device or a policy based on the
target storage caching.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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Anand Jain 2020-10-28 21:14:46 +08:00 • committed by David Sterba

parent aaefed2078

commit 33fd2f714c

2 changed files with 26 additions and 1 deletions

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14

fs/btrfs/volumes.c

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13

fs/btrfs/volumes.h

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