From: Linus Torvalds <torvalds@linux-foundation.org>
To: Borislav Petkov <bp@alien8.de>
Cc: David Howells <dhowells@redhat.com>,
kernel test robot <oliver.sang@intel.com>,
oe-lkp@lists.linux.dev, lkp@intel.com,
linux-kernel@vger.kernel.org,
Christian Brauner <brauner@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
Christian Brauner <christian@brauner.io>,
Matthew Wilcox <willy@infradead.org>,
David Laight <David.Laight@aculab.com>,
ying.huang@intel.com, feng.tang@intel.com, fengwei.yin@intel.com
Subject: Re: [linus:master] [iov_iter] c9eec08bac: vm-scalability.throughput -16.9% regression
Date: Wed, 15 Nov 2023 15:07:24 -0500 [thread overview]
Message-ID: <CAHk-=whrc-ruKs4Kt90EGzKd+pYhZFKs6bgBVCV=55BK+p1nzg@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=whFW+uWOmOtRNh0What_fu8Xo8KF2+EeUH1kn4qFxGAhA@mail.gmail.com>
On Wed, 15 Nov 2023 at 14:15, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> So my patch really is broken. It might happen to work when everything
> else goes right, and it's small, but it is very much a "proof of
> concept" rather than something that is actually acceptable.
More breakage details
(a) need to not do this with the boot code and EFI stub code that
doesn't handle alternatives.
It's not a huge deal in that obviously both alternatives work,
but it causes build issues:
ld: error: unplaced orphan section `.altinstructions' from
`arch/x86/boot/compressed/misc.o'
ld: error: unplaced orphan section `.altinstr_replacement' from
`arch/x86/boot/compressed/misc.o'
...
etc
- our current "memcpy_orig" fallback does unrolled copy loops, and
the rep_movs_alternative fallback obviously doesn't.
It's not clear that the unrolled copy loops matter for the in-kernel
kinds of copies, but who knows. The memcpy_orig code is definitely
trying to be smarter in some other ways too. So the fallback should
try a *bit* harder than I did, and not just with the whole "don't try
to handle exceptions" issue I mentioned.
Linus
next prev parent reply other threads:[~2023-11-15 20:07 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-07 1:40 [linus:master] [iov_iter] c9eec08bac: vm-scalability.throughput -16.9% regression kernel test robot
2023-11-15 12:48 ` David Howells
2023-11-15 13:18 ` David Howells
2023-11-15 15:20 ` David Howells
2023-11-15 16:53 ` Linus Torvalds
2023-11-15 17:38 ` Linus Torvalds
2023-11-15 18:38 ` Linus Torvalds
2023-11-15 19:09 ` Borislav Petkov
2023-11-15 19:15 ` Linus Torvalds
2023-11-15 20:07 ` Linus Torvalds [this message]
2023-11-16 10:07 ` David Laight
2023-11-16 10:14 ` David Howells
2023-11-16 11:38 ` David Laight
2023-11-15 19:26 ` Linus Torvalds
2023-11-16 15:44 ` Borislav Petkov
2023-11-16 16:48 ` Linus Torvalds
2023-11-16 16:58 ` David Laight
2023-11-17 11:44 ` Borislav Petkov
2023-11-17 12:09 ` Jakub Jelinek
2023-11-17 12:18 ` Borislav Petkov
2023-11-17 13:09 ` David Laight
2023-11-17 13:36 ` Linus Torvalds
2023-11-17 15:20 ` David Laight
2023-11-16 16:44 ` David Howells
2023-11-17 11:35 ` Borislav Petkov
2023-11-17 14:12 ` David Howells
2023-11-17 16:09 ` Borislav Petkov
2023-11-17 16:32 ` Linus Torvalds
2023-11-17 16:44 ` Linus Torvalds
2023-11-17 19:12 ` Borislav Petkov
2023-11-17 21:57 ` Linus Torvalds
2023-11-20 13:32 ` David Howells
2023-11-20 16:06 ` Linus Torvalds
2023-11-20 16:09 ` David Laight
2023-11-15 21:43 ` David Howells
2023-11-15 21:50 ` Linus Torvalds
2023-11-15 21:59 ` Borislav Petkov
2023-11-20 11:52 ` Borislav Petkov
2023-11-15 22:59 ` David Howells
2023-11-16 3:26 ` Linus Torvalds
2023-11-16 16:55 ` David Laight
2023-11-16 17:24 ` Linus Torvalds
2023-11-16 22:53 ` David Laight
2023-11-16 21:09 ` David Howells
2023-11-16 22:36 ` Linus Torvalds
2023-11-15 18:35 ` David Howells
2023-11-15 18:45 ` Linus Torvalds
2023-11-15 19:09 ` Linus Torvalds
2023-11-15 20:54 ` David Howells
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='CAHk-=whrc-ruKs4Kt90EGzKd+pYhZFKs6bgBVCV=55BK+p1nzg@mail.gmail.com' \
--to=torvalds@linux-foundation.org \
--cc=David.Laight@aculab.com \
--cc=axboe@kernel.dk \
--cc=bp@alien8.de \
--cc=brauner@kernel.org \
--cc=christian@brauner.io \
--cc=dhowells@redhat.com \
--cc=feng.tang@intel.com \
--cc=fengwei.yin@intel.com \
--cc=hch@lst.de \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@intel.com \
--cc=oe-lkp@lists.linux.dev \
--cc=oliver.sang@intel.com \
--cc=viro@zeniv.linux.org.uk \
--cc=willy@infradead.org \
--cc=ying.huang@intel.com \
/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).