From: Andrew Morton <akpm@linux-foundation.org>
To: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Nitin Gupta <ngupta@vflare.org>, Minchan Kim <minchan@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Dan Magenheimer <dan.magenheimer@oracle.com>,
Robert Jennings <rcj@linux.vnet.ibm.com>,
Jenifer Hopper <jhopper@us.ibm.com>, Mel Gorman <mgorman@suse.de>,
Johannes Weiner <jweiner@redhat.com>,
Rik van Riel <riel@redhat.com>,
Larry Woodman <lwoodman@redhat.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Dave Hansen <dave@linux.vnet.ibm.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
devel@driverdev.osuosl.org
Subject: Re: [PATCHv4 6/7] zswap: add flushing support
Date: Tue, 29 Jan 2013 15:03:50 -0800 [thread overview]
Message-ID: <20130129150350.d0b51ca9.akpm@linux-foundation.org> (raw)
In-Reply-To: <1359495627-30285-7-git-send-email-sjenning@linux.vnet.ibm.com>
On Tue, 29 Jan 2013 15:40:26 -0600
Seth Jennings <sjenning@linux.vnet.ibm.com> wrote:
> This patchset adds support for flush pages out of the compressed
> pool to the swap device
I do so hate that word "flush". Sometimes it means "writeback", other
times it means "invalidate". And perhaps it means "copy elsewhere then
reclaim".
Please describe with great specificity what this patch actually does
with pages, and why it does it. And where the compression factors into
this.
The code appears to take a compressed page, decompress it into
swapcache via some means. And then, for unexplained reasons, it starts
writeback of that swapcache page.
In zswap_flush_entry() there is a comment "page is already in the swap
cache, ignore for now". This is very interesting. How and why does
this come about? Does it imply that there are two copies of the same
data floating around? If so, how come?
Preferably all the above would be understandable by reading mm/zswap.c.
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next prev parent reply other threads:[~2013-01-29 23:03 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-29 21:40 [PATCHv4 0/7] zswap: compressed swap caching Seth Jennings
2013-01-29 21:40 ` [PATCHv4 1/7] debugfs: add get/set for atomic types Seth Jennings
2013-01-29 21:40 ` [PATCHv4 2/7] zsmalloc: promote to lib/ Seth Jennings
2013-01-29 22:51 ` Andrew Morton
2013-01-30 16:28 ` Seth Jennings
2013-01-30 23:34 ` Andrew Morton
2013-01-31 5:35 ` Minchan Kim
2013-02-13 16:00 ` Seth Jennings
2013-01-29 21:40 ` [PATCHv4 3/7] zswap: add to mm/ Seth Jennings
2013-01-31 7:07 ` Minchan Kim
2013-01-31 19:06 ` Seth Jennings
2013-01-31 20:07 ` Robert Jennings
2013-02-01 2:38 ` Minchan Kim
2013-02-01 15:31 ` Seth Jennings
2013-02-01 17:46 ` Seth Jennings
2013-01-29 21:40 ` [PATCHv4 4/7] mm: break up swap_writepage() for frontswap backends Seth Jennings
2013-01-29 21:40 ` [PATCHv4 5/7] mm: allow for outstanding swap writeback accounting Seth Jennings
2013-01-29 21:40 ` [PATCHv4 6/7] zswap: add flushing support Seth Jennings
2013-01-29 23:03 ` Andrew Morton [this message]
2013-02-01 7:27 ` Minchan Kim
2013-02-13 6:24 ` Seth Jennings
2013-01-29 21:40 ` [PATCHv4 7/7] zswap: add documentation Seth Jennings
2013-01-29 23:07 ` Andrew Morton
2013-01-29 22:14 ` [PATCHv4 0/7] zswap: compressed swap caching Joe Perches
2013-01-29 22:49 ` Seth Jennings
2013-01-30 4:32 ` Minchan Kim
2013-01-30 16:01 ` Seth Jennings
2013-02-01 1:39 ` Simon Jeons
2013-02-01 15:13 ` Seth Jennings
2013-02-03 0:17 ` Simon Jeons
2013-02-04 14:56 ` Seth Jennings
2013-02-04 1:03 ` Simon Jeons
2013-02-04 15:07 ` Seth Jennings
[not found] ` <5110287A.5050200@linux.vnet.ibm.com>
2013-02-04 21:45 ` Seth Jennings
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