From: Matthew Wilcox <willy@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
sergey.senozhatsky@gmail.com, iamjoonsoo.kim@lge.com,
ngupta@vflare.org, zhouxianrong@huawei.com, zhouxiyu@huawei.com,
weidu.du@huawei.com, zhangshiming5@huawei.com,
Mi.Sophia.Wang@huawei.com, won.ho.park@huawei.com
Subject: Re: memfill
Date: Tue, 7 Feb 2017 09:22:58 -0800 [thread overview]
Message-ID: <20170207172258.GM2267@bombadil.infradead.org> (raw)
In-Reply-To: <27995.1486460404@warthog.procyon.org.uk>
On Tue, Feb 07, 2017 at 09:40:04AM +0000, David Howells wrote:
> Matthew Wilcox <willy@infradead.org> wrote:
>
> > [adding linux-arch to see if anyone there wants to do an optimised
> > version of memfill for their CPU]
>
> For mn10300, this is superfluous since the memset() implementation will do
> optimised filling of up to 8 x 4 bytes per loop if the alignments suit.
>
> This is also superfluous for frv as that will do up to 8 x 8 bytes per loop.
>
> So on both those arches, memfill() should probably just wrap memset().
You've misunderstood the purpose of memfill. memfill allows the caller
to specify a pattern which is not a single byte in size, eg memfill(addr,
0x12345678, 64) would result in 0x12345678 being reproduced 16 times.
memset(addr, 0x12345678, 64) would result in 0x78 being reproduced
64 times.
next prev parent reply other threads:[~2017-02-07 17:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-05 15:16 [PATCH v4] zram: extend zero pages to same element pages Minchan Kim
2017-02-06 14:49 ` memfill Matthew Wilcox
2017-02-07 2:47 ` memfill zhouxianrong
2017-02-07 4:59 ` memfill Minchan Kim
2017-02-07 19:07 ` memfill James Bottomley
2017-02-08 18:04 ` memfill Matthew Wilcox
2017-02-08 21:01 ` memfill James Bottomley
2017-02-08 21:54 ` memfill Matthew Wilcox
2017-02-07 6:57 ` [PATCH v4] zram: extend zero pages to same element pages Minchan Kim
2017-02-07 9:40 ` memfill David Howells
2017-02-07 17:22 ` Matthew Wilcox [this message]
2017-02-07 17:29 ` memfill David Howells
2017-02-07 19:03 ` memfill Matthew Wilcox
2017-03-11 14:56 ` memfill v2 now with ARM and x86 implementations Matthew Wilcox
2017-03-13 5:17 ` Minchan Kim
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