From: David Laight <David.Laight@ACULAB.COM>
To: 'Linus Torvalds' <torvalds@linux-foundation.org>
Cc: Andrew Lutomirski <luto@kernel.org>,
"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: Mon, 26 Nov 2018 10:26:08 +0000 [thread overview]
Message-ID: <a3ebeca68de1493f876467f57575be74@AcuMS.aculab.com> (raw)
In-Reply-To: <CAHk-=wj9DA-mH8jahuEPUWxO4EgbCcPRgdOJAQD58DBtCCrHcQ@mail.gmail.com>
From: Linus Torvalds
> Sent: 23 November 2018 16:36
...
> End result: we *used* to do this right. For the last eight years our
> "memcpy_{to,from}io()" has been entirely broken, and apparently even
> the people who noticed oddities like David, never reported it as
> breakage but instead just worked around it in drivers.
I've mentioned it several times...
Probably no one else noticed lots of single byte transfers while
testing a TLP monitor he was writing for an FPGA :-)
They are far too expensive to buy, and would never be connected
to the right system at the right time - so we (I) wrote one.
Unfortunately we don't really get to see what happens when the
link comes up (or rather doesn't come up). We only get the
LTSSM state transitions.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2018-11-26 10:26 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
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 [this message]
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
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