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From: Minchan Kim <minchan@kernel.org>
To: Jan Kara <jack@suse.cz>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ying Huang <ying.huang@intel.com>,
	dave.hansen@intel.com, ak@linux.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>,
	Rik van Riel <riel@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Hillf Danton <hillf.zj@alibaba-inc.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Peter Zijlstra <peterz@infradead.org>,
	Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH v4 0/9] mm/swap: Regular page swap optimizations
Date: Tue, 3 Jan 2017 13:34:11 +0900	[thread overview]
Message-ID: <20170103043411.GA15657@bbox> (raw)
In-Reply-To: <20170102154841.GG18058@quack2.suse.cz>

Hi Jan,

On Mon, Jan 02, 2017 at 04:48:41PM +0100, Jan Kara wrote:
> Hi,
> 
> On Tue 27-12-16 16:45:03, Minchan Kim wrote:
> > > Patch 3 splits the swap cache radix tree into 64MB chunks, reducing
> > >         the rate that we have to contende for the radix tree.
> > 
> > To me, it's rather hacky. I think it might be common problem for page cache
> > so can we think another generalized way like range_lock? Ccing Jan.
> 
> I agree on the hackyness of the patch and that page cache would suffer with
> the same contention (although the files are usually smaller than swap so it
> would not be that visible I guess). But I don't see how range lock would
> help here - we need to serialize modifications of the tree structure itself
> and that is difficult to achieve with the range lock. So what you would
> need is either a different data structure for tracking swap cache entries
> or a finer grained locking of the radix tree.

Thanks for the comment, Jan.

I think there are more general options. One is to shrink batching pages like
Mel and Tim had approached.

https://patchwork.kernel.org/patch/9008421/
https://patchwork.kernel.org/patch/9322793/

Or concurrent page cache by peter.

https://www.kernel.org/doc/ols/2007/ols2007v2-pages-311-318.pdf

Ccing Nick who might have an interest on lockless page cache.

Thanks.

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  reply	other threads:[~2017-01-03  4:34 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-09 21:09 Tim Chen
2016-12-09 21:09 ` [PATCH v4 1/9] mm/swap: Fix kernel message in swap_info_get() Tim Chen
2016-12-09 21:09 ` [PATCH v4 2/9] mm/swap: Add cluster lock Tim Chen
2016-12-09 21:09 ` [PATCH v4 3/9] mm/swap: Split swap cache into 64MB trunks Tim Chen
2016-12-09 21:09 ` [PATCH v4 4/9] mm/swap: skip read ahead for unreferenced swap slots Tim Chen
2016-12-09 21:09 ` [PATCH v4 5/9] mm/swap: Allocate swap slots in batches Tim Chen
2016-12-09 21:09 ` [PATCH v4 6/9] mm/swap: Free swap slots in batch Tim Chen
2016-12-09 21:09 ` [PATCH v4 7/9] mm/swap: Add cache for swap slots allocation Tim Chen
2016-12-09 21:09 ` [PATCH v4 8/9] mm/swap: Enable swap slots cache usage Tim Chen
2016-12-09 21:09 ` [PATCH v4 9/9] mm/swap: Skip readahead only when swap slot cache is enabled Tim Chen
2016-12-27  7:45 ` [PATCH v4 0/9] mm/swap: Regular page swap optimizations Minchan Kim
2016-12-28  1:54   ` Huang, Ying
2016-12-28  2:37     ` Minchan Kim
2016-12-28  3:15       ` Huang, Ying
2016-12-28  3:31         ` Huang, Ying
2016-12-28  3:53           ` Minchan Kim
2016-12-28  4:56             ` Huang, Ying
2017-01-02 15:48   ` Jan Kara
2017-01-03  4:34     ` Minchan Kim [this message]
2017-01-03  5:43       ` Huang, Ying
2017-01-05  6:15         ` Minchan Kim
2017-01-03 17:47       ` Tim Chen
2017-01-05  1:33   ` Huang, Ying
2017-01-05  6:32     ` Minchan Kim
2017-01-05  6:44       ` Huang, Ying

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