[Gluster-devel] Changing the relative order of read-ahead and open-behind

[Vijay Bellur]

On Fri, Jul 21, 2017 at 3:26 AM, Raghavendra Gowdappa <rgowdapp at redhat.com>
wrote:

> Hi all,
>
> We've a bug [1], due to which read-ahead is completely disabled when the
> workload is read-only. One of the easy fix was to make read-ahead as an
> ancestor of open-behind in xlator graph (Currently its a descendant). A
> patch has been sent out by Rafi to do the same. As noted in one of the
> comments, one flip side of this solution is that small files (which are
> eligible to be cached by quick read) are cached twice - once each in
> read-ahead and quick-read - wasting up precious memory. However, there are
> no other simpler solutions for this issue. If you've concerns on the
> approach followed by [2] or have other suggestions please voice them out.
> Otherwise, I am planning to merge [2] for lack of better alternatives.
>


Since the maximum size of files cached by quick-read is 64KB, can we have
read-ahead kick in for offsets greater than 64KB?

Thanks,
Vijay
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