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 ` 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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome