From: Cody P Schafer <cody@linux.vnet.ibm.com>
To: Pekka Enberg <penberg@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Gilad Ben-Yossef <gilad@benyossef.com>,
Simon Jeons <simon.jeons@gmail.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Mel Gorman <mgorman@suse.de>, Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RESEND v3 00/11] mm: fixup changers of per cpu pageset's ->high and ->batch
Date: Mon, 13 May 2013 13:47:27 -0700 [thread overview]
Message-ID: <5191515F.8020406@linux.vnet.ibm.com> (raw)
In-Reply-To: <CAOJsxLF7xCiJmNn71zuNPGx1WzSj2BKeMVGXctfzvZODqVVU-A@mail.gmail.com>
On 05/13/2013 12:20 PM, Pekka Enberg wrote:
> Hi Cody,
>
> On Mon, May 13, 2013 at 10:08 PM, Cody P Schafer
> <cody@linux.vnet.ibm.com> wrote:
>> "Problems" with the current code:
>> 1. there is a lack of synchronization in setting ->high and ->batch in
>> percpu_pagelist_fraction_sysctl_handler()
>> 2. stop_machine() in zone_pcp_update() is unnecissary.
>> 3. zone_pcp_update() does not consider the case where percpu_pagelist_fraction is non-zero
>
> Maybe it's just me but I find the above problem description confusing.
> How does the problem manifest itself?
1. I've not reproduced this causing issues.
2. Calling zone_pcp_update() is slow.
3. Not reproduced either, but would cause percpu_pagelist_fraction (set
via sysctl) to be ignored after a call to zone_pcp_update() (for
example, after a memory hotplug).
> How did you find about it?
I'm writing some code that resizes zones and thus uses
zone_pcp_update(), and fixing broken things along the way.
> Why
> do we need to fix all three problems in the same patch set?
They all affect the same bit of code and fixing all of them means
restructuring the both of the sites where ->high and ->batch are set.
Additionally, splitting it out (if possible) would make it less clear
what the overall goal is, and would mean a few inter-patchset
dependencies, which are undesirable.
--
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>
prev parent reply other threads:[~2013-05-13 20:48 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-13 19:08 Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 01/11] mm/page_alloc: factor out setting of pcp->high and pcp->batch Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 02/11] mm/page_alloc: prevent concurrent updaters of pcp ->batch and ->high Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 03/11] mm/page_alloc: insert memory barriers to allow async update of pcp batch and high Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 04/11] mm/page_alloc: protect pcp->batch accesses with ACCESS_ONCE Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 05/11] mm/page_alloc: convert zone_pcp_update() to rely on memory barriers instead of stop_machine() Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 06/11] mm/page_alloc: when handling percpu_pagelist_fraction, don't unneedly recalulate high Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 07/11] mm/page_alloc: factor setup_pageset() into pageset_init() and pageset_set_batch() Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 08/11] mm/page_alloc: relocate comment to be directly above code it refers to Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 09/11] mm/page_alloc: factor zone_pageset_init() out of setup_zone_pageset() Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 10/11] mm/page_alloc: in zone_pcp_update(), uze zone_pageset_init() Cody P Schafer
2013-05-13 19:08 ` [PATCH RESEND v3 11/11] mm/page_alloc: rename setup_pagelist_highmark() to match naming of pageset_set_batch() Cody P Schafer
2013-05-13 19:20 ` [PATCH RESEND v3 00/11] mm: fixup changers of per cpu pageset's ->high and ->batch Pekka Enberg
2013-05-13 20:47 ` Cody P Schafer [this message]
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=5191515F.8020406@linux.vnet.ibm.com \
--to=cody@linux.vnet.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=gilad@benyossef.com \
--cc=kosaki.motohiro@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=penberg@kernel.org \
--cc=simon.jeons@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