From: Hugh Dickins <hughd@google.com>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Andi Kleen <andi@firstfloor.org>,
Wu Fengguang <fengguang.wu@intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/6] thp: optimize away unnecessary page table locking
Date: Sun, 19 Feb 2012 13:21:02 -0800 (PST) [thread overview]
Message-ID: <alpine.LSU.2.00.1202191316320.1466@eggly.anvils> (raw)
In-Reply-To: <1328716302-16871-3-git-send-email-n-horiguchi@ah.jp.nec.com>
On Wed, 8 Feb 2012, Naoya Horiguchi wrote:
> Currently when we check if we can handle thp as it is or we need to
> split it into regular sized pages, we hold page table lock prior to
> check whether a given pmd is mapping thp or not. Because of this,
> when it's not "huge pmd" we suffer from unnecessary lock/unlock overhead.
> To remove it, this patch introduces a optimized check function and
> replace several similar logics with it.
>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: David Rientjes <rientjes@google.com>
>
> Changes since v4:
> - Rethink returned value of __pmd_trans_huge_lock()
[snip]
> --- 3.3-rc2.orig/mm/mremap.c
> +++ 3.3-rc2/mm/mremap.c
> @@ -155,8 +155,6 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
> if (err > 0) {
> need_flush = true;
> continue;
> - } else if (!err) {
> - split_huge_page_pmd(vma->vm_mm, old_pmd);
> }
> VM_BUG_ON(pmd_trans_huge(*old_pmd));
> }
Is that what you intended to do there?
I just hit that VM_BUG_ON on rc3-next-20120217.
Hugh
next prev parent reply other threads:[~2012-02-19 21:21 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-08 15:51 [PATCH 0/6 v5] pagemap handles transparent hugepage Naoya Horiguchi
2012-02-08 15:51 ` [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap Naoya Horiguchi
2012-02-08 15:51 ` [PATCH 2/6] thp: optimize away unnecessary page table locking Naoya Horiguchi
2012-02-09 2:19 ` KAMEZAWA Hiroyuki
2012-02-19 21:21 ` Hugh Dickins [this message]
2012-02-20 7:28 ` Naoya Horiguchi
2012-02-20 11:38 ` Hugh Dickins
2012-02-20 11:54 ` Jiri Slaby
2012-02-08 15:51 ` [PATCH 3/6] pagemap: export KPF_THP Naoya Horiguchi
2012-02-08 15:51 ` [PATCH 4/6] pagemap: document KPF_THP and make page-types aware of it Naoya Horiguchi
2012-02-08 15:51 ` [PATCH 5/6] introduce pmd_to_pte_t() Naoya Horiguchi
2012-02-09 2:24 ` KAMEZAWA Hiroyuki
2012-02-16 0:54 ` Andrew Morton
2012-02-16 9:02 ` Naoya Horiguchi
2012-02-08 15:51 ` [PATCH 6/6] pagemap: introduce data structure for pagemap entry Naoya Horiguchi
2012-02-09 2:29 ` KAMEZAWA Hiroyuki
2012-02-09 4:16 ` Naoya Horiguchi
2012-02-10 0:27 ` Andrew Morton
2012-02-10 0:59 ` KAMEZAWA Hiroyuki
-- strict thread matches above, loose matches on Subject: below --
2012-01-27 23:02 [PATCH 0/6 v4] pagemap handles transparent hugepage Naoya Horiguchi
2012-01-27 23:02 ` [PATCH 2/6] thp: optimize away unnecessary page table locking Naoya Horiguchi
2012-01-28 11:23 ` Hillf Danton
2012-01-28 22:33 ` Naoya Horiguchi
2012-01-30 6:22 ` KAMEZAWA Hiroyuki
2012-02-02 5:27 ` Naoya Horiguchi
2012-02-02 8:32 ` KAMEZAWA Hiroyuki
2012-01-16 17:19 Naoya Horiguchi
2012-01-12 19:34 [PATCH 0/6 v3] pagemap handles transparent hugepage Naoya Horiguchi
2012-01-12 19:34 ` [PATCH 2/6] thp: optimize away unnecessary page table locking Naoya Horiguchi
2012-01-13 12:04 ` Hillf Danton
2012-01-13 15:14 ` Naoya Horiguchi
2012-01-14 3:24 ` Hillf Danton
2012-01-14 17:19 ` Andrea Arcangeli
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=alpine.LSU.2.00.1202191316320.1466@eggly.anvils \
--to=hughd@google.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=andi@firstfloor.org \
--cc=fengguang.wu@intel.com \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=kosaki.motohiro@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=n-horiguchi@ah.jp.nec.com \
--cc=rientjes@google.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).