From: Christoph Hellwig <hch@lst.de>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Chuck Lever III <chuck.lever@oracle.com>,
Mark Hemment <markhemm@googlemail.com>,
Patrice CHOTARD <patrice.chotard@foss.st.com>,
Mikulas Patocka <mpatocka@redhat.com>,
Lukas Czerner <lczerner@redhat.com>,
Christoph Hellwig <hch@lst.de>,
"Darrick J. Wong" <djwong@kernel.org>,
linux-mm@kvack.org, linux-nfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com,
viro@zeniv.linux.org.uk
Subject: Re: [PATCH] tmpfs: fix regressions from wider use of ZERO_PAGE
Date: Sat, 9 Apr 2022 07:06:38 +0200 [thread overview]
Message-ID: <20220409050638.GB17755@lst.de> (raw)
In-Reply-To: <9a978571-8648-e830-5735-1f4748ce2e30@google.com>
On Fri, Apr 08, 2022 at 01:38:41PM -0700, Hugh Dickins wrote:
> + } else if (iter_is_iovec(to)) {
> + /*
> + * Copy to user tends to be so well optimized, but
> + * clear_user() not so much, that it is noticeably
> + * faster to copy the zero page instead of clearing.
> + */
> + ret = copy_page_to_iter(ZERO_PAGE(0), offset, nr, to);
Is the offset and length guaranteed to be less than PAGE_SIZE here?
Either way I'd rather do this optimization in iov_iter_zero rather
than hiding it in tmpfs.
next prev parent reply other threads:[~2022-04-09 5:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-08 20:38 [PATCH] tmpfs: fix regressions from wider use of ZERO_PAGE Hugh Dickins
2022-04-09 5:06 ` Christoph Hellwig [this message]
2022-04-09 6:08 ` Hugh Dickins
2022-04-12 4:57 ` making x86 clear_user not suck, was " Christoph Hellwig
2022-04-13 18:06 ` Matthew Wilcox
2022-04-12 23:22 ` Andrew Morton
2022-04-13 16:41 ` Christoph Hellwig
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=20220409050638.GB17755@lst.de \
--to=hch@lst.de \
--cc=akpm@linux-foundation.org \
--cc=chuck.lever@oracle.com \
--cc=djwong@kernel.org \
--cc=hughd@google.com \
--cc=lczerner@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-nfs@vger.kernel.org \
--cc=linux-stm32@st-md-mailman.stormreply.com \
--cc=markhemm@googlemail.com \
--cc=mpatocka@redhat.com \
--cc=patrice.chotard@foss.st.com \
--cc=viro@zeniv.linux.org.uk \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).