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From: Timofey Titovets <nefelim4ag@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
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 16:33:43 +0300
Message-ID: <CAGqmi77nDU+z2PhNFJq3i208mxMbdTdk2=uPwfj42y0G3yyiWw@mail.gmail.com> (raw)
In-Reply-To: <20171018123427.GA7271@bombadil.infradead.org>

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));
> }
>
> (and you should see significantly better numbers at least on x86;
> I don't know if anyone's done an arm64 version of memset_l yet).
>
> --
> 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>

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)

Thanks.
-- 
Have a nice day,
Timofey.

--
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  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 [this message]
2017-10-18 14:11       ` Matthew Wilcox
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

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