From: Christoph Hellwig <hch@infradead.org>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] iov_iter: optimise iter type checking
Date: Thu, 19 Nov 2020 17:03:40 +0000 [thread overview]
Message-ID: <20201119170340.GA6179@infradead.org> (raw)
In-Reply-To: <9bc27cb3ef6ab49b6b2ccee3db6613838aee17af.1605799583.git.asml.silence@gmail.com>
On Thu, Nov 19, 2020 at 03:29:43PM +0000, Pavel Begunkov wrote:
> The problem here is that iov_iter_is_*() helpers check types for
> equality, but all iterate_* helpers do bitwise ands. This confuses
> a compiler, so even if some cases were handled separately with
> iov_iter_is_*(), it can't eliminate and skip unreachable branches in
> following iterate*().
I think we need to kill the iov_iter_is_* helpers, renumber to not do
the pointless bitmask and just check for equality (might turn into a
bunch of nice switch statements actually).
next prev parent reply other threads:[~2020-11-19 17:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 15:29 [PATCH 0/2] optimise iov_iter Pavel Begunkov
2020-11-19 15:29 ` [PATCH 1/2] iov_iter: optimise iov_iter_npages for bvec Pavel Begunkov
2020-11-19 15:29 ` [PATCH 2/2] iov_iter: optimise iter type checking Pavel Begunkov
2020-11-19 17:03 ` Christoph Hellwig [this message]
2020-11-19 17:12 ` Pavel Begunkov
2020-12-11 2:01 ` Al Viro
2020-12-13 22:32 ` Pavel Begunkov
2020-12-14 10:28 ` David Laight
2020-12-14 17:25 ` Pavel Begunkov
2020-11-19 16:46 ` [PATCH 0/2] optimise iov_iter Jens Axboe
2020-11-19 17:14 ` Pavel Begunkov
2020-11-19 17:20 ` Jens Axboe
2020-11-19 18:02 ` Pavel Begunkov
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=20201119170340.GA6179@infradead.org \
--to=hch@infradead.org \
--cc=asml.silence@gmail.com \
--cc=axboe@kernel.dk \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.