From: Peter Xu <peterx@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Linux-MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Marty Mcfadden <mcfadden8@llnl.gov>,
"Maya B . Gokhale" <gokhale2@llnl.gov>,
Jann Horn <jannh@google.com>, Christoph Hellwig <hch@lst.de>,
Oleg Nesterov <oleg@redhat.com>,
Kirill Shutemov <kirill@shutemov.name>, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH v3] mm/gup: Allow real explicit breaking of COW
Date: Thu, 20 Aug 2020 22:34:25 -0400 [thread overview]
Message-ID: <CADLectmG+ZEaE7g4wY2P9pQRJrm+_MpS+2CL=A3g+6=9F9GA6Q@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wjGzOjsfmX1Dc=yz6o_+62w4wcTVXX_hia9sHLfsCoxjg@mail.gmail.com>
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Yep. I'll run some test and update soon.
Thanks,
Peter
On Thu., Aug. 20, 2020, 18:01 Linus Torvalds <torvalds@linux-foundation.org>
wrote:
> On Thu, Aug 20, 2020 at 2:54 PM Peter Xu <peterx@redhat.com> wrote:
> >
> > I kind of prefer the new suggestion to remove code rather than adding new
> > codes. I definitely don't know enough on the side effect of it,
> especially
> > performance-wise on either ksm or swap, but... IIUC the worst case is
> we'll get
> > some perf report later on, and it seems also not hard to revert the
> patch later
> > if we want.
>
> Well, would you be willing to try this patch out?
>
> After you apply that patch, you should be able to remove the
> should_force_cow_break() games entirely, because a write to the page
> should always break cow towards the writer if there are any GUP users
> around (put another way: away from the GUP).
>
> However, to make the test meaningful, it really should do some swap
> testing too.
>
> Linus
>
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next prev parent reply other threads:[~2020-08-21 2:34 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 18:39 Peter Xu
2020-08-11 19:07 ` Jann Horn
2020-08-11 20:02 ` Peter Xu
2020-08-11 20:22 ` Jann Horn
2020-08-11 21:23 ` Peter Xu
2020-08-11 19:24 ` Linus Torvalds
2020-08-11 20:06 ` Linus Torvalds
2020-08-11 20:46 ` Linus Torvalds
2020-08-11 21:42 ` Peter Xu
2020-08-11 23:10 ` Linus Torvalds
2020-08-20 21:54 ` Peter Xu
2020-08-20 22:01 ` Linus Torvalds
2020-08-21 2:34 ` Peter Xu [this message]
2020-08-21 10:13 ` Jan Kara
2020-08-21 12:27 ` Linus Torvalds
2020-08-21 15:47 ` Jan Kara
2020-08-21 17:00 ` Linus Torvalds
2020-08-21 18:08 ` Peter Xu
2020-08-21 18:23 ` Linus Torvalds
2020-08-21 19:05 ` Linus Torvalds
2020-08-21 19:06 ` Linus Torvalds
2020-08-21 19:31 ` Peter Xu
2020-08-21 19:42 ` Linus Torvalds
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