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From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Huang, Ying" <ying.huang@intel.com>,
	tim.c.chen@intel.com, dave.hansen@intel.com,
	andi.kleen@intel.com, aaron.lu@intel.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Hugh Dickins <hughd@google.com>,
	Shaohua Li <shli@kernel.org>, Minchan Kim <minchan@kernel.org>,
	Rik van Riel <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
	Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH -v2] mm: Don't use radix tree writeback tags for pages in swap cache
Date: Thu, 1 Sep 2016 09:51:11 +0100	[thread overview]
Message-ID: <20160901085111.GC8119@techsingularity.net> (raw)
In-Reply-To: <20160831143031.4e5a180f969ec6997637a96f@linux-foundation.org>

On Wed, Aug 31, 2016 at 02:30:31PM -0700, Andrew Morton wrote:
> On Wed, 31 Aug 2016 10:14:59 +0100 Mel Gorman <mgorman@techsingularity.net> wrote:
> 
> > >    2506952 __  2%     +28.1%    3212076 __  7%  vm-scalability.throughput
> > >    1207402 __  7%     +22.3%    1476578 __  6%  vmstat.swap.so
> > >      10.86 __ 12%     -23.4%       8.31 __ 16%  perf-profile.cycles-pp._raw_spin_lock_irq.__add_to_swap_cache.add_to_swap_cache.add_to_swap.shrink_page_list
> > >      10.82 __ 13%     -33.1%       7.24 __ 14%  perf-profile.cycles-pp._raw_spin_lock_irqsave.__remove_mapping.shrink_page_list.shrink_inactive_list.shrink_zone_memcg
> > >      10.36 __ 11%    -100.0%       0.00 __ -1%  perf-profile.cycles-pp._raw_spin_lock_irqsave.__test_set_page_writeback.bdev_write_page.__swap_writepage.swap_writepage
> > >      10.52 __ 12%    -100.0%       0.00 __ -1%  perf-profile.cycles-pp._raw_spin_lock_irqsave.test_clear_page_writeback.end_page_writeback.page_endio.pmem_rw_page
> > > 
> > 
> > I didn't see anything wrong with the patch but it's worth highlighting
> > that this hunk means we are now out of GFP bits.
> 
> Well ugh.  What are we to do about that?
> 

It'll stop silent breakage so

Acked-by: Mel Gorman <mgorman@techsingularity.net>

Whoever hits it will need to take similar steps we had to with page->flags
by making some 64-bit only, removing flags or inferring the flag values
from other sources.

-- 
Mel Gorman
SUSE Labs

WARNING: multiple messages have this Message-ID
From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Huang, Ying" <ying.huang@intel.com>,
	tim.c.chen@intel.com, dave.hansen@intel.com,
	andi.kleen@intel.com, aaron.lu@intel.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Hugh Dickins <hughd@google.com>,
	Shaohua Li <shli@kernel.org>, Minchan Kim <minchan@kernel.org>,
	Rik van Riel <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
	Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH -v2] mm: Don't use radix tree writeback tags for pages in swap cache
Date: Thu, 1 Sep 2016 09:51:11 +0100	[thread overview]
Message-ID: <20160901085111.GC8119@techsingularity.net> (raw)
In-Reply-To: <20160831143031.4e5a180f969ec6997637a96f@linux-foundation.org>

On Wed, Aug 31, 2016 at 02:30:31PM -0700, Andrew Morton wrote:
> On Wed, 31 Aug 2016 10:14:59 +0100 Mel Gorman <mgorman@techsingularity.net> wrote:
> 
> > >    2506952 __  2%     +28.1%    3212076 __  7%  vm-scalability.throughput
> > >    1207402 __  7%     +22.3%    1476578 __  6%  vmstat.swap.so
> > >      10.86 __ 12%     -23.4%       8.31 __ 16%  perf-profile.cycles-pp._raw_spin_lock_irq.__add_to_swap_cache.add_to_swap_cache.add_to_swap.shrink_page_list
> > >      10.82 __ 13%     -33.1%       7.24 __ 14%  perf-profile.cycles-pp._raw_spin_lock_irqsave.__remove_mapping.shrink_page_list.shrink_inactive_list.shrink_zone_memcg
> > >      10.36 __ 11%    -100.0%       0.00 __ -1%  perf-profile.cycles-pp._raw_spin_lock_irqsave.__test_set_page_writeback.bdev_write_page.__swap_writepage.swap_writepage
> > >      10.52 __ 12%    -100.0%       0.00 __ -1%  perf-profile.cycles-pp._raw_spin_lock_irqsave.test_clear_page_writeback.end_page_writeback.page_endio.pmem_rw_page
> > > 
> > 
> > I didn't see anything wrong with the patch but it's worth highlighting
> > that this hunk means we are now out of GFP bits.
> 
> Well ugh.  What are we to do about that?
> 

It'll stop silent breakage so

Acked-by: Mel Gorman <mgorman@techsingularity.net>

Whoever hits it will need to take similar steps we had to with page->flags
by making some 64-bit only, removing flags or inferring the flag values
from other sources.

-- 
Mel Gorman
SUSE Labs

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  reply	other threads:[~2016-09-01  8:52 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-30 17:28 Huang, Ying
2016-08-30 17:28 ` Huang, Ying
2016-08-30 18:29 ` Rik van Riel
2016-08-31  9:14 ` Mel Gorman
2016-08-31  9:14   ` Mel Gorman
2016-08-31 15:17   ` Huang, Ying
2016-08-31 15:17     ` Huang, Ying
2016-08-31 15:39     ` Mel Gorman
2016-08-31 15:39       ` Mel Gorman
2016-08-31 15:44       ` Huang, Ying
2016-08-31 15:44         ` Huang, Ying
2016-08-31 21:35       ` Andi Kleen
2016-08-31 21:35         ` Andi Kleen
2016-08-31 21:30   ` Andrew Morton
2016-08-31 21:30     ` Andrew Morton
2016-09-01  8:51     ` Mel Gorman [this message]
2016-09-01  8:51       ` Mel Gorman
2016-09-01  9:13     ` Michal Hocko
2016-09-01  9:13       ` Michal Hocko
2016-09-12 11:16       ` [PATCH 0/2] do not squash mapping flags and gfp_mask together (was: Re: [PATCH -v2] mm: Don't use radix tree writeback tags for pages in) Michal Hocko
2016-09-12 11:16         ` Michal Hocko
2016-09-12 11:16         ` [PATCH 1/2] fs: use mapping_set_error instead of opencoded set_bit Michal Hocko
2016-09-12 11:16           ` Michal Hocko
2016-09-12 22:11           ` Andrew Morton
2016-09-12 22:11             ` Andrew Morton
2016-09-12 22:18             ` Andrew Morton
2016-09-12 22:18               ` Andrew Morton
2016-09-13  6:53               ` Michal Hocko
2016-09-13  6:53                 ` Michal Hocko
2016-09-13 21:29                 ` Andrew Morton
2016-09-13 21:29                   ` Andrew Morton
2016-09-12 11:16         ` [PATCH 2/2] mm: split gfp_mask and mapping flags into separate fields Michal Hocko
2016-09-12 11:16           ` Michal Hocko
2016-09-12 11:48           ` Michal Hocko
2016-09-12 11:48             ` Michal Hocko

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