Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
From: Matthew Wilcox <willy@infradead.org>
To: Timofey Titovets <nefelim4ag@gmail.com>
Cc: Srividya Desireddy <srividya.dr@samsung.com>,
	"sjenning@redhat.com" <sjenning@redhat.com>,
	"ddstreet@ieee.org" <ddstreet@ieee.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"penberg@kernel.org" <penberg@kernel.org>,
	Dinakar Reddy Pathireddy <dinakar.p@samsung.com>,
	SHARAN ALLUR <sharan.allur@samsung.com>,
	RAJIB BASU <rajib.basu@samsung.com>,
	JUHUN KIM <juhunkim@samsung.com>,
	"srividya.desireddy@gmail.com" <srividya.desireddy@gmail.com>
Subject: Re: [PATCH] zswap: Same-filled pages handling
Date: Wed, 18 Oct 2017 07:11:16 -0700
Message-ID: <20171018141116.GA12063@bombadil.infradead.org> (raw)
In-Reply-To: <CAGqmi77nDU+z2PhNFJq3i208mxMbdTdk2=uPwfj42y0G3yyiWw@mail.gmail.com>

On Wed, Oct 18, 2017 at 04:33:43PM +0300, Timofey Titovets wrote:
> 2017-10-18 15:34 GMT+03:00 Matthew Wilcox <willy@infradead.org>:
> > On Wed, Oct 18, 2017 at 10:48:32AM +0000, Srividya Desireddy wrote:
> >> +static void zswap_fill_page(void *ptr, unsigned long value)
> >> +{
> >> +     unsigned int pos;
> >> +     unsigned long *page;
> >> +
> >> +     page = (unsigned long *)ptr;
> >> +     if (value == 0)
> >> +             memset(page, 0, PAGE_SIZE);
> >> +     else {
> >> +             for (pos = 0; pos < PAGE_SIZE / sizeof(*page); pos++)
> >> +                     page[pos] = value;
> >> +     }
> >> +}
> >
> > I think you meant:
> >
> > static void zswap_fill_page(void *ptr, unsigned long value)
> > {
> >         memset_l(ptr, value, PAGE_SIZE / sizeof(unsigned long));
> > }
> 
> IIRC kernel have special zero page, and if i understand correctly.
> You can map all zero pages to that zero page and not touch zswap completely.
> (Your situation look like some KSM case (i.e. KSM can handle pages
> with same content), but i'm not sure if that applicable there)

You're confused by the word "same".  What Srividya meant was that the
page is filled with a pattern, eg 0xfffefffefffefffe..., not that it is
the same as any other page.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1>
2017-10-18 10:48 ` Srividya Desireddy
2017-10-18 12:34   ` Matthew Wilcox
2017-10-18 13:33     ` Timofey Titovets
2017-10-18 14:11       ` Matthew Wilcox [this message]
2017-10-18 20:43   ` Andi Kleen
2017-10-19  1:10     ` Matthew Wilcox
2017-10-19  4:30       ` Andi Kleen
2017-10-19 13:24         ` Matthew Wilcox
2017-10-18 21:31   ` Timofey Titovets
2017-10-19  1:08     ` Matthew Wilcox
     [not found]     ` <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p3>
2017-11-02 15:08       ` Srividya Desireddy
2017-11-17 22:10         ` Dan Streetman
2017-11-17 22:07     ` Dan Streetman
2017-11-17 21:27   ` Dan Streetman
2017-11-20 23:46   ` Andrew Morton
2017-11-28 11:35     ` Dan Streetman
     [not found]     ` <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p6>
2017-11-29 15:34       ` [PATCH] zswap: Update with same-value filled page feature Srividya Desireddy
2017-11-29 21:29         ` Dan Streetman
2017-12-06 11:48       ` [PATCH v2] " Srividya Desireddy
2017-12-06 15:20         ` Dan Streetman
     [not found]   ` <CGME20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p4>
2017-11-21 14:18     ` [PATCH v2] zswap: Same-filled pages handling Srividya Desireddy
2017-10-18 14:43 ` [PATCH] " Srividya Desireddy

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20171018141116.GA12063@bombadil.infradead.org \
    --to=willy@infradead.org \
    --cc=ddstreet@ieee.org \
    --cc=dinakar.p@samsung.com \
    --cc=juhunkim@samsung.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=nefelim4ag@gmail.com \
    --cc=penberg@kernel.org \
    --cc=rajib.basu@samsung.com \
    --cc=sharan.allur@samsung.com \
    --cc=sjenning@redhat.com \
    --cc=srividya.desireddy@gmail.com \
    --cc=srividya.dr@samsung.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git