From: David Laight <David.Laight@ACULAB.COM>
To: 'Linus Torvalds' <torvalds@linux-foundation.org>,
Andrew Lutomirski <luto@kernel.org>
Cc: "dvlasenk@redhat.com" <dvlasenk@redhat.com>,
Jens Axboe <axboe@kernel.dk>, Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>, "bp@alien8.de" <bp@alien8.de>,
Peter Anvin <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"brgerst@gmail.com" <brgerst@gmail.com>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
"pabeni@redhat.com" <pabeni@redhat.com>
Subject: RE: [PATCH] x86: only use ERMS for user copies for larger sizes
Date: Fri, 23 Nov 2018 09:34:49 +0000 [thread overview]
Message-ID: <cd11d9423c8b46ecbf97753f8317c294@AcuMS.aculab.com> (raw)
In-Reply-To: <CAHk-=wiEUVpSU-GxpKDvN9wnH2yDxkJgE7Vqh46A+fmnvhubyw@mail.gmail.com>
From: Linus Torvalds
> Sent: 22 November 2018 18:58
...
> Oh, and I just noticed that on x86 we expressly use our old "safe and
> sane" functions: see __inline_memcpy(), and its use in
> __memcpy_{from,to}io().
>
> So the "falls back to memcpy" was always a red herring. We don't
> actually do that.
>
> Which explains why things work.
It doesn't explain why I've seen single byte PCIe TLP generated
by memcpy_to/fromio().
I've had to change code to use readq/writeq loops because the
byte accesses are so slow - even when PIO performance should
be 'good enough'.
It might have been changed since last time I tested it.
But I don't remember seeing a commit go by.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2018-11-23 9:34 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <02bfc577-32a5-66be-64bf-d476b7d447d2@kernel.dk>
2018-11-20 20:24 ` [PATCH] x86: only use ERMS for user copies for larger sizes Jens Axboe
2018-11-21 6:36 ` Ingo Molnar
2018-11-21 13:32 ` Jens Axboe
2018-11-21 13:44 ` Denys Vlasenko
2018-11-22 17:36 ` David Laight
2018-11-22 17:52 ` Linus Torvalds
2018-11-22 18:06 ` Andy Lutomirski
2018-11-22 18:58 ` Linus Torvalds
2018-11-23 9:34 ` David Laight [this message]
2018-11-23 10:12 ` David Laight
2018-11-23 16:36 ` Linus Torvalds
2018-11-23 17:42 ` Linus Torvalds
2018-11-23 18:39 ` Andy Lutomirski
2018-11-23 18:44 ` Linus Torvalds
2018-11-23 19:11 ` Andy Lutomirski
2018-11-26 10:12 ` David Laight
2018-11-26 10:01 ` David Laight
2018-11-26 10:26 ` David Laight
2019-01-05 2:38 ` Linus Torvalds
2019-01-07 9:55 ` David Laight
2019-01-07 17:43 ` Linus Torvalds
2019-01-08 9:10 ` David Laight
2019-01-08 18:01 ` Linus Torvalds
2018-11-21 13:45 ` Paolo Abeni
2018-11-21 17:27 ` Linus Torvalds
2018-11-21 18:04 ` Jens Axboe
2018-11-21 18:26 ` Andy Lutomirski
2018-11-21 18:43 ` Linus Torvalds
2018-11-21 22:38 ` Andy Lutomirski
2018-11-21 18:16 ` Linus Torvalds
2018-11-21 19:01 ` Linus Torvalds
2018-11-22 10:32 ` Ingo Molnar
2018-11-22 11:13 ` Ingo Molnar
2018-11-22 11:21 ` Ingo Molnar
2018-11-23 16:40 ` Josh Poimboeuf
2018-11-22 16:55 ` Linus Torvalds
2018-11-22 17:26 ` Andy Lutomirski
2018-11-22 17:35 ` Linus Torvalds
2018-11-24 6:09 ` Jens Axboe
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=cd11d9423c8b46ecbf97753f8317c294@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=bp@alien8.de \
--cc=brgerst@gmail.com \
--cc=dvlasenk@redhat.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@kernel.org \
--cc=mingo@redhat.com \
--cc=pabeni@redhat.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/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.