Re: [PATCH] z3fold: make pages_nr atomic

On Fri, Nov 4, 2016 at 3:27 AM, Vitaly Wool [off-list ref] wrote:

On Thu, Nov 3, 2016 at 11:17 PM, Andrew Morton
[off-list ref] wrote:

quoted

On Thu, 3 Nov 2016 22:24:07 +0100 Vitaly Wool [off-list ref] wrote:

quoted

On Thu, Nov 3, 2016 at 10:14 PM, Andrew Morton
[off-list ref] wrote:

quoted

On Thu, 3 Nov 2016 22:00:58 +0100 Vitaly Wool [off-list ref] wrote:

quoted

This patch converts pages_nr per-pool counter to atomic64_t.

Which is slower.

Presumably there is a reason for making this change.  This reason
should be described in the changelog.

The reason [which I thought was somewhat obvious :) ] is that there
won't be a need to take a per-pool lock to read or modify that
counter.

But the patch didn't change the locking.  And as far as I can tell,
neither does "z3fold: extend compaction function".

Right. I'll come up with the locking rework shortly, but it will be a
RFC so I wanted to send it separately.

this is still in mmotm, and it seems the later patches rely on it, so
while i agree that the changelog should be clearer about why it's
needed, the change itself looks ok.

Acked-by: Dan Streetman <redacted>

~vitaly

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