All of lore.kernel.org
 help / color / mirror / Atom feed
From: Ingo Molnar <mingo@kernel.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>,
	Minchan Kim <minchan@kernel.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Andi Kleen <andi@firstfloor.org>, H Peter Anvin <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/4] mm: Send one IPI per CPU to TLB flush all entries after unmapping pages
Date: Thu, 11 Jun 2015 17:02:51 +0200	[thread overview]
Message-ID: <20150611150250.GA14086@gmail.com> (raw)
In-Reply-To: <20150610085950.GB26425@suse.de>


* Mel Gorman <mgorman@suse.de> wrote:

> > In the full-flushing case (v6 without patch 4) the batching limit is 
> > 'infinite', we'll batch as long as possible, right?
> 
> No because we must flush before pages are freed so the maximum batching is 
> related to SWAP_CLUSTER_MAX. If we free a page before the flush then in theory 
> the page can be reallocated and a stale TLB entry can allow access to unrelated 
> data. It would be almost impossible to trigger corruption this way but it's a 
> concern.

Well, could we say double SWAP_CLUSTER_MAX to further reduce the IPI rate?

Thanks,

	Ingo

--
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>

WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>,
	Minchan Kim <minchan@kernel.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Andi Kleen <andi@firstfloor.org>, H Peter Anvin <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/4] mm: Send one IPI per CPU to TLB flush all entries after unmapping pages
Date: Thu, 11 Jun 2015 17:02:51 +0200	[thread overview]
Message-ID: <20150611150250.GA14086@gmail.com> (raw)
In-Reply-To: <20150610085950.GB26425@suse.de>


* Mel Gorman <mgorman@suse.de> wrote:

> > In the full-flushing case (v6 without patch 4) the batching limit is 
> > 'infinite', we'll batch as long as possible, right?
> 
> No because we must flush before pages are freed so the maximum batching is 
> related to SWAP_CLUSTER_MAX. If we free a page before the flush then in theory 
> the page can be reallocated and a stale TLB entry can allow access to unrelated 
> data. It would be almost impossible to trigger corruption this way but it's a 
> concern.

Well, could we say double SWAP_CLUSTER_MAX to further reduce the IPI rate?

Thanks,

	Ingo

  reply	other threads:[~2015-06-11 15:02 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-09 17:31 [PATCH 0/3] TLB flush multiple pages per IPI v6 Mel Gorman
2015-06-09 17:31 ` Mel Gorman
2015-06-09 17:31 ` [PATCH 1/4] x86, mm: Trace when an IPI is about to be sent Mel Gorman
2015-06-09 17:31   ` Mel Gorman
2015-06-09 17:31 ` [PATCH 2/4] mm: Send one IPI per CPU to TLB flush all entries after unmapping pages Mel Gorman
2015-06-09 17:31   ` Mel Gorman
2015-06-09 20:01   ` Rik van Riel
2015-06-09 20:01     ` Rik van Riel
2015-06-10  7:47   ` Ingo Molnar
2015-06-10  7:47     ` Ingo Molnar
2015-06-10  8:14     ` Mel Gorman
2015-06-10  8:14       ` Mel Gorman
2015-06-10  8:21       ` Ingo Molnar
2015-06-10  8:21         ` Ingo Molnar
2015-06-10  8:51         ` Mel Gorman
2015-06-10  8:51           ` Mel Gorman
2015-06-10  8:26   ` Ingo Molnar
2015-06-10  8:26     ` Ingo Molnar
2015-06-10  9:58     ` Mel Gorman
2015-06-10  9:58       ` Mel Gorman
2015-06-10  8:33   ` Ingo Molnar
2015-06-10  8:33     ` Ingo Molnar
2015-06-10  8:59     ` Mel Gorman
2015-06-10  8:59       ` Mel Gorman
2015-06-11 15:02       ` Ingo Molnar [this message]
2015-06-11 15:02         ` Ingo Molnar
2015-06-11 15:25         ` Mel Gorman
2015-06-11 15:25           ` Mel Gorman
2015-06-09 17:31 ` [PATCH 3/4] mm: Defer flush of writable TLB entries Mel Gorman
2015-06-09 17:31   ` Mel Gorman
2015-06-09 20:02   ` Rik van Riel
2015-06-09 20:02     ` Rik van Riel
2015-06-10  7:50   ` Ingo Molnar
2015-06-10  7:50     ` Ingo Molnar
2015-06-10  8:17     ` Mel Gorman
2015-06-10  8:17       ` Mel Gorman
2015-06-09 17:31 ` [PATCH 4/4] mm: Send one IPI per CPU to TLB flush pages that were recently unmapped Mel Gorman
2015-06-09 17:31   ` Mel Gorman
  -- strict thread matches above, loose matches on Subject: below --
2015-07-06 13:39 [PATCH 0/4] TLB flush multiple pages per IPI v7 Mel Gorman
2015-07-06 13:39 ` [PATCH 2/4] mm: Send one IPI per CPU to TLB flush all entries after unmapping pages Mel Gorman
2015-07-06 13:39   ` Mel Gorman

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=20150611150250.GA14086@gmail.com \
    --to=mingo@kernel.org \
    --cc=a.p.zijlstra@chello.nl \
    --cc=akpm@linux-foundation.org \
    --cc=andi@firstfloor.org \
    --cc=dave.hansen@intel.com \
    --cc=hpa@zytor.com \
    --cc=hughd@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mgorman@suse.de \
    --cc=minchan@kernel.org \
    --cc=riel@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.