Re: [PATCH v2] fadvise: perform WILLNEED readahead asynchronously

From: Eric Wong
Date: Wed Jan 09 2013 - 23:05:42 EST


Simon Jeons <simon.jeons@xxxxxxxxx> wrote:
> On Tue, 2012-12-25 at 02:22 +0000, Eric Wong wrote:
>
> Please add changelog.

Changes since v1:

* separate unbound workqueue for high-priority tasks

* account for inflight readahead to avoid denial-of-service

* limit concurrency for non-high-priority tasks (1 per CPU, same as aio)

* take IO priority of requesting process into account when in workqueue.

* process queued readahead in 2M chunks to help ensure fairness between
multiple requests with few CPUs/workqueues. Idle tasks get smaller
256K chunks.

* stops readahead for idle tasks on read congestion

Will try to benchmark with Postgres when I get the chance.

Any other (Free Software) applications that might benefit from
lower FADV_WILLNEED latency?
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