From: Minchan Kim <minchan@kernel.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Michal Hocko <mhocko@kernel.org>,
Christoph Lameter <cl@linux.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>, <kernel-team@lge.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: copy_page() on a kmalloc-ed page with DEBUG_SLAB enabled (was "zram: do not use copy_page with non-page alinged address")
Date: Thu, 20 Apr 2017 15:50:28 +0900 [thread overview]
Message-ID: <20170420065028.GA3847@bbox> (raw)
In-Reply-To: <20170420014542.GA542@jagdpanzerIV.localdomain>
On Thu, Apr 20, 2017 at 10:45:42AM +0900, Sergey Senozhatsky wrote:
> On (04/19/17 04:51), Matthew Wilcox wrote:
> [..]
> > > > > Another approach is the API does normal thing for non-aligned prefix and
> > > > > tail space and fast thing for aligned space.
> > > > > Otherwise, it would be happy if the API has WARN_ON non-page SIZE aligned
> > > > > address.
> >
> > Why not just use memcpy()? Is copy_page() significantly faster than
> > memcpy() for a PAGE_SIZE amount of data?
>
> that's a good point.
>
> I was going to ask yesterday - do we even need copy_page()? arch that
> provides well optimized copy_page() quite likely provides somewhat
> equally optimized memcpy(). so may be copy_page() is not even needed?
I don't know.
Just I found https://download.samba.org/pub/paulus/ols-2003-presentation.pdf
and heard https://lkml.org/lkml/2017/4/10/1270.
next prev parent reply other threads:[~2017-04-20 6:51 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-17 1:48 copy_page() on a kmalloc-ed page with DEBUG_SLAB enabled (was "zram: do not use copy_page with non-page alinged address") Sergey Senozhatsky
2017-04-17 15:20 ` Christoph Lameter
2017-04-18 0:03 ` Minchan Kim
2017-04-18 7:33 ` Michal Hocko
2017-04-18 10:56 ` Sergey Senozhatsky
2017-04-18 11:06 ` Michal Hocko
2017-04-19 6:11 ` Sergey Senozhatsky
2017-04-19 6:02 ` Minchan Kim
2017-04-19 11:51 ` Matthew Wilcox
2017-04-20 1:45 ` Sergey Senozhatsky
2017-04-20 6:50 ` Minchan Kim [this message]
2017-04-18 10:42 ` Sergey Senozhatsky
2017-04-18 13:28 ` Christoph Lameter
2017-04-18 13:13 ` Matthew Wilcox
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