From: Rik van Riel <riel@redhat.com>
To: Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>, Mel Gorman <mgorman@suse.de>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch 1/2] mm: page-writeback: fix dirty_balance_reserve subtraction from dirtyable memory
Date: Fri, 24 Jan 2014 18:05:09 -0500 [thread overview]
Message-ID: <52E2F1A5.7010907@redhat.com> (raw)
In-Reply-To: <1390600984-13925-2-git-send-email-hannes@cmpxchg.org>
On 01/24/2014 05:03 PM, Johannes Weiner wrote:
> The dirty_balance_reserve is an approximation of the fraction of free
> pages that the page allocator does not make available for page cache
> allocations. As a result, it has to be taken into account when
> calculating the amount of "dirtyable memory", the baseline to which
> dirty_background_ratio and dirty_ratio are applied.
>
> However, currently the reserve is subtracted from the sum of free and
> reclaimable pages, which is non-sensical and leads to erroneous
> results when the system is dominated by unreclaimable pages and the
> dirty_balance_reserve is bigger than free+reclaimable. In that case,
> at least the already allocated cache should be considered dirtyable.
>
> Fix the calculation by subtracting the reserve from the amount of free
> pages, then adding the reclaimable pages on top.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>, Mel Gorman <mgorman@suse.de>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch 1/2] mm: page-writeback: fix dirty_balance_reserve subtraction from dirtyable memory
Date: Fri, 24 Jan 2014 18:05:09 -0500 [thread overview]
Message-ID: <52E2F1A5.7010907@redhat.com> (raw)
In-Reply-To: <1390600984-13925-2-git-send-email-hannes@cmpxchg.org>
On 01/24/2014 05:03 PM, Johannes Weiner wrote:
> The dirty_balance_reserve is an approximation of the fraction of free
> pages that the page allocator does not make available for page cache
> allocations. As a result, it has to be taken into account when
> calculating the amount of "dirtyable memory", the baseline to which
> dirty_background_ratio and dirty_ratio are applied.
>
> However, currently the reserve is subtracted from the sum of free and
> reclaimable pages, which is non-sensical and leads to erroneous
> results when the system is dominated by unreclaimable pages and the
> dirty_balance_reserve is bigger than free+reclaimable. In that case,
> at least the already allocated cache should be considered dirtyable.
>
> Fix the calculation by subtracting the reserve from the amount of free
> pages, then adding the reclaimable pages on top.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
--
All rights reversed
next prev parent reply other threads:[~2014-01-24 23:05 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-24 22:03 [patch 0/2] mm: reduce reclaim stalls with heavy anon and dirty cache Johannes Weiner
2014-01-24 22:03 ` Johannes Weiner
2014-01-24 22:03 ` [patch 1/2] mm: page-writeback: fix dirty_balance_reserve subtraction from dirtyable memory Johannes Weiner
2014-01-24 22:03 ` Johannes Weiner
2014-01-24 23:05 ` Rik van Riel [this message]
2014-01-24 23:05 ` Rik van Riel
2014-01-28 13:48 ` Michal Hocko
2014-01-28 13:48 ` Michal Hocko
2014-01-24 22:03 ` [patch 2/2] mm: page-writeback: do not count anon pages as " Johannes Weiner
2014-01-24 22:03 ` Johannes Weiner
2014-01-24 23:25 ` Rik van Riel
2014-01-24 23:25 ` Rik van Riel
2014-01-28 13:58 ` Michal Hocko
2014-01-28 13:58 ` Michal Hocko
2014-01-24 22:21 ` [patch 0/2] mm: reduce reclaim stalls with heavy anon and dirty cache Tejun Heo
2014-01-24 22:21 ` Tejun Heo
2014-01-24 23:31 ` Tejun Heo
2014-01-24 22:30 ` Andrew Morton
2014-01-24 22:30 ` Andrew Morton
2014-01-24 22:51 ` Johannes Weiner
2014-01-24 22:51 ` Johannes Weiner
2014-01-24 23:26 ` Rik van Riel
2014-01-24 23:26 ` Rik van Riel
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