All of lore.kernel.org
 help / color / mirror / Atom feed
From: Michal Hocko <mhocko@kernel.org>
To: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm, sparse: do not swamp log with huge vmemmap allocation failures
Date: Mon, 6 Nov 2017 19:18:35 +0100	[thread overview]
Message-ID: <20171106181835.yfngqffiuwzrjtmu@dhcp22.suse.cz> (raw)
In-Reply-To: <1509992067.4140.1.camel@oracle.com>

On Mon 06-11-17 11:14:27, Khalid Aziz wrote:
> On Mon, 2017-11-06 at 10:22 +0100, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@suse.com>
> > 
> > While doing a memory hotplug tests under a heavy memory pressure we
> > have
> > noticed too many page allocation failures when allocating vmemmap
> > memmap
> > backed by huge page
> > ......... deleted .........
> > +
> > +		if (!warned) {
> > +			warn_alloc(gfp_mask, NULL, "vmemmap alloc
> > failure: order:%u", order);
> > +			warned = true;
> > +		}
> >  		return NULL;
> >  	} else
> >  		return __earlyonly_bootmem_alloc(node, size, size,
> 
> This will warn once and only once after a kernel is booted. This
> condition may happen repeatedly over a long period of time with
> significant time span between two such events and it can be useful to
> know if this is happening repeatedly. There might be better ways to
> throttle the rate of warnings, something like warn once and then
> suppress warnings for the next 15 minutes (or pick any other time
> frame). If this condition happens again later, there will be another
> warning.

While this is all true I am not sure we care all that much. The failure
mode is basically not using an optimization. This is not something we
warn normally about. Even the performance degradation is a theoretical
concern which nobody has backed by real life numbers AFAIR.

If we want to make it more sophisticated I would expect some numbers to
back such a change.
-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID
From: Michal Hocko <mhocko@kernel.org>
To: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm, sparse: do not swamp log with huge vmemmap allocation failures
Date: Mon, 6 Nov 2017 19:18:35 +0100	[thread overview]
Message-ID: <20171106181835.yfngqffiuwzrjtmu@dhcp22.suse.cz> (raw)
In-Reply-To: <1509992067.4140.1.camel@oracle.com>

On Mon 06-11-17 11:14:27, Khalid Aziz wrote:
> On Mon, 2017-11-06 at 10:22 +0100, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@suse.com>
> > 
> > While doing a memory hotplug tests under a heavy memory pressure we
> > have
> > noticed too many page allocation failures when allocating vmemmap
> > memmap
> > backed by huge page
> > ......... deleted .........
> > +
> > +		if (!warned) {
> > +			warn_alloc(gfp_mask, NULL, "vmemmap alloc
> > failure: order:%u", order);
> > +			warned = true;
> > +		}
> >  		return NULL;
> >  	} else
> >  		return __earlyonly_bootmem_alloc(node, size, size,
> 
> This will warn once and only once after a kernel is booted. This
> condition may happen repeatedly over a long period of time with
> significant time span between two such events and it can be useful to
> know if this is happening repeatedly. There might be better ways to
> throttle the rate of warnings, something like warn once and then
> suppress warnings for the next 15 minutes (or pick any other time
> frame). If this condition happens again later, there will be another
> warning.

While this is all true I am not sure we care all that much. The failure
mode is basically not using an optimization. This is not something we
warn normally about. Even the performance degradation is a theoretical
concern which nobody has backed by real life numbers AFAIR.

If we want to make it more sophisticated I would expect some numbers to
back such a change.
-- 
Michal Hocko
SUSE Labs

--
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>

  reply	other threads:[~2017-11-06 18:18 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-06  9:22 Michal Hocko
2017-11-06  9:22 ` Michal Hocko
2017-11-06 17:35 ` Johannes Weiner
2017-11-06 17:35   ` Johannes Weiner
2017-11-06 17:57   ` Joe Perches
2017-11-06 18:14 ` Khalid Aziz
2017-11-06 18:14   ` Khalid Aziz
2017-11-06 18:18   ` Michal Hocko [this message]
2017-11-06 18:18     ` Michal Hocko
2017-11-06 20:17     ` Khalid Aziz
2017-11-06 20:17       ` Khalid Aziz
2017-11-07  9:06 ` Michal Hocko
2017-11-07  9:06   ` Michal Hocko
2017-11-06 20:56 [RFC PATCH for 4.15 00/14] Restartable sequences and CPU op vector v10 Mathieu Desnoyers
2017-11-06 20:56 ` Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH v10 for 4.15 01/14] Restartable sequences system call Mathieu Desnoyers
2017-11-07  1:24   ` Boqun Feng
2017-11-07  1:24     ` Boqun Feng
2017-11-07  2:20     ` Mathieu Desnoyers
2017-11-07  2:20       ` Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH for 4.15 02/14] Restartable sequences: ARM 32 architecture support Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH for 4.15 03/14] Restartable sequences: wire up ARM 32 system call Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH for 4.15 04/14] Restartable sequences: x86 32/64 architecture support Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH for 4.15 05/14] Restartable sequences: wire up x86 32/64 system call Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH for 4.15 06/14] Restartable sequences: powerpc architecture support Mathieu Desnoyers
2017-11-06 20:56   ` Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH for 4.15 07/14] Restartable sequences: Wire up powerpc system call Mathieu Desnoyers
2017-11-06 20:56   ` Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH v2 for 4.15 08/14] Provide cpu_opv " Mathieu Desnoyers
2017-11-07  2:07   ` Boqun Feng
2017-11-07  2:07     ` Boqun Feng
2017-11-07  2:40     ` Mathieu Desnoyers
2017-11-07  2:40       ` Mathieu Desnoyers
2017-11-07  3:03       ` Boqun Feng
2017-11-07  3:03         ` Boqun Feng
2017-11-06 20:56 ` [RFC PATCH for 4.15 09/14] cpu_opv: Wire up x86 32/64 " Mathieu Desnoyers
2017-11-06 20:56   ` Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH for 4.15 10/14] cpu_opv: Wire up powerpc " Mathieu Desnoyers
2017-11-06 20:56   ` Mathieu Desnoyers
2017-11-07  0:37   ` Nicholas Piggin
2017-11-07  0:37     ` Nicholas Piggin
2017-11-07  0:47     ` Mathieu Desnoyers
2017-11-07  0:47       ` Mathieu Desnoyers
2017-11-07  1:21       ` Nicholas Piggin
2017-11-07  1:21         ` Nicholas Piggin
2017-11-06 20:56 ` [RFC PATCH for 4.15 11/14] cpu_opv: Wire up ARM32 " Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH v2 for 4.15 12/14] cpu_opv: Implement selftests Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH v2 for 4.15 13/14] Restartable sequences: Provide self-tests Mathieu Desnoyers
2017-11-06 20:56   ` Mathieu Desnoyers
2017-11-06 20:56 ` [RFC PATCH for 4.15 14/14] Restartable sequences selftests: arm: workaround gcc asm size guess Mathieu Desnoyers
2017-11-06 20:56   ` Mathieu Desnoyers

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=20171106181835.yfngqffiuwzrjtmu@dhcp22.suse.cz \
    --to=mhocko@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=hannes@cmpxchg.org \
    --cc=khalid.aziz@oracle.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=vbabka@suse.cz \
    --subject='Re: [PATCH] mm, sparse: do not swamp log with huge vmemmap allocation failures' \
    /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

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.