From: Andy Lutomirski <luto@kernel.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Nadav Amit <nadav.amit@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>
Subject: Re: Potential race in TLB flush batching?
Date: Sat, 15 Jul 2017 09:41:35 -0700 [thread overview]
Message-ID: <CALCETrWbvt2n2PLtsVM5RgCKz+RZ30STFS2xZ=dacPZRwokFHw@mail.gmail.com> (raw)
In-Reply-To: <20170715155518.ok2q62efc2vurqk5@suse.de>
On Sat, Jul 15, 2017 at 8:55 AM, Mel Gorman <mgorman@suse.de> wrote:
> The patch looks fine to be but when writing the patch, I wondered why the
> original code disabled preemption before inc_mm_tlb_gen. I didn't spot
> the reason for it but given the importance of properly synchronising with
> switch_mm, I played it safe. However, this should be ok on top and
> maintain the existing sequences
LGTM. You could also fold it into your patch or even put it before
your patch, too.
FWIW, I didn't have any real reason to inc_mm_tlb_gen() with
preemption disabled. I think I did it because the code it replaced
was also called with preemption off. That being said, it's
effectively a single instruction, so it barely matters latency-wise.
(Hmm. Would there be a performance downside if a thread got preempted
between inc_mm_tlb_gen() and doing the flush? It could arbitrarily
delay the IPIs, which would give a big window for something else to
flush and maybe make our IPIs unnecessary. Whether that's a win or a
loss isn't so clear to me.)
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-07-15 16:41 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-11 0:52 Potential race in TLB flush batching? Nadav Amit
2017-07-11 6:41 ` Mel Gorman
2017-07-11 7:30 ` Nadav Amit
2017-07-11 9:29 ` Mel Gorman
2017-07-11 10:40 ` Nadav Amit
2017-07-11 13:20 ` Mel Gorman
2017-07-11 14:58 ` Andy Lutomirski
2017-07-11 15:53 ` Mel Gorman
2017-07-11 17:23 ` Andy Lutomirski
2017-07-11 19:18 ` Mel Gorman
2017-07-11 20:06 ` Nadav Amit
2017-07-11 21:09 ` Mel Gorman
2017-07-11 20:09 ` Mel Gorman
2017-07-11 21:52 ` Mel Gorman
2017-07-11 22:27 ` Nadav Amit
2017-07-11 22:34 ` Nadav Amit
2017-07-12 8:27 ` Mel Gorman
2017-07-12 23:27 ` Nadav Amit
2017-07-12 23:36 ` Andy Lutomirski
2017-07-12 23:42 ` Nadav Amit
2017-07-13 5:38 ` Andy Lutomirski
2017-07-13 16:05 ` Nadav Amit
2017-07-13 16:06 ` Andy Lutomirski
2017-07-13 6:07 ` Mel Gorman
2017-07-13 16:08 ` Andy Lutomirski
2017-07-13 17:07 ` Mel Gorman
2017-07-13 17:15 ` Andy Lutomirski
2017-07-13 18:23 ` Mel Gorman
2017-07-14 23:16 ` Nadav Amit
2017-07-15 15:55 ` Mel Gorman
2017-07-15 16:41 ` Andy Lutomirski [this message]
2017-07-17 7:49 ` Mel Gorman
2017-07-18 21:28 ` Nadav Amit
2017-07-19 7:41 ` Mel Gorman
2017-07-19 19:41 ` Nadav Amit
2017-07-19 19:58 ` Mel Gorman
2017-07-19 20:20 ` Nadav Amit
2017-07-19 21:47 ` Mel Gorman
2017-07-19 22:19 ` Nadav Amit
2017-07-19 22:59 ` Mel Gorman
2017-07-19 23:39 ` Nadav Amit
2017-07-20 7:43 ` Mel Gorman
2017-07-22 1:19 ` Nadav Amit
2017-07-24 9:58 ` Mel Gorman
2017-07-24 19:46 ` Nadav Amit
2017-07-25 7:37 ` Minchan Kim
2017-07-25 8:51 ` Mel Gorman
2017-07-25 9:11 ` Minchan Kim
2017-07-25 10:10 ` Mel Gorman
2017-07-26 5:43 ` Minchan Kim
2017-07-26 9:22 ` Mel Gorman
2017-07-26 19:18 ` Nadav Amit
2017-07-26 23:40 ` Minchan Kim
2017-07-27 0:09 ` Nadav Amit
2017-07-27 0:34 ` Minchan Kim
2017-07-27 0:48 ` Nadav Amit
2017-07-27 1:13 ` Nadav Amit
2017-07-27 7:04 ` Minchan Kim
2017-07-27 7:21 ` Mel Gorman
2017-07-27 16:04 ` Nadav Amit
2017-07-27 17:36 ` Mel Gorman
2017-07-26 23:44 ` Minchan Kim
2017-07-11 22:07 ` Andy Lutomirski
2017-07-11 22:33 ` Mel Gorman
2017-07-14 7:00 ` Benjamin Herrenschmidt
2017-07-14 8:31 ` Mel Gorman
2017-07-14 9:02 ` Benjamin Herrenschmidt
2017-07-14 9:27 ` Mel Gorman
2017-07-14 22:21 ` Andy Lutomirski
2017-07-11 16:22 ` Nadav Amit
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='CALCETrWbvt2n2PLtsVM5RgCKz+RZ30STFS2xZ=dacPZRwokFHw@mail.gmail.com' \
--to=luto@kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=nadav.amit@gmail.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).