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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Hugh Dickins <hughd@google.com>,
	"hannes@cmpxchg.org" <hannes@cmpxchg.org>
Subject: Re: [PATCH RFC 00/15] mm: memory book keeping and lru_lock splitting
Date: Thu, 16 Feb 2012 11:04:08 +0900	[thread overview]
Message-ID: <20120216110408.f35c3448.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <20120215224221.22050.80605.stgit@zurg>

On Thu, 16 Feb 2012 02:57:04 +0400
Konstantin Khlebnikov <khlebnikov@openvz.org> wrote:

> There should be no logic changes in this patchset, this is only tossing bits around.
> [ This patchset is on top some memcg cleanup/rework patches,
>   which I sent to linux-mm@ today/yesterday ]
> 
> Most of things in this patchset are self-descriptive, so here brief plan:
> 

AFAIK, Hugh Dickins said he has per-zone-per-lru-lock and is testing it.
So, please CC him and Johannes, at least.


> * Transmute struct lruvec into struct book. Like real book this struct will
>   store set of pages for one zone. It will be working unit for reclaimer code.
> [ If memcg is disabled in config there will only one book embedded into struct zone ]
> 

Why you need to add new structure rahter than enhancing lruvec ?
"book" means a binder of pages ?


> * move page-lru counters to struct book
> [ this adds extra overhead in add_page_to_lru_list()/del_page_from_lru_list() for
>   non-memcg case, but I believe it will be invisible, only one non-atomic add/sub
>   in the same cacheline with lru list ]
> 

This seems straightforward.

> * unify inactive_list_is_low_global() and cleanup reclaimer code
> * replace struct mem_cgroup_zone with single pointer to struct book

Hm, ok.

> * optimize page to book translations, move it upper in the call stack,
>   replace some struct zone arguments with struct book pointer.
> 

a page->book transrater from patch 2/15

+struct book *page_book(struct page *page)
+{
+	struct mem_cgroup_per_zone *mz;
+	struct page_cgroup *pc;
+
+	if (mem_cgroup_disabled())
+		return &page_zone(page)->book;
+
+	pc = lookup_page_cgroup(page);
+	if (!PageCgroupUsed(pc))
+		return &page_zone(page)->book;
+	/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
+	smp_rmb();
+	mz = mem_cgroup_zoneinfo(pc->mem_cgroup,
+			page_to_nid(page), page_zonenum(page));
+	return &mz->book;
+}

What happens when pc->mem_cgroup is rewritten by move_account() ?
Where is the guard for lockless access of this ?

Thanks,
-Kame

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  parent reply	other threads:[~2012-02-16  2:05 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-15 22:57 Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 01/15] mm: rename struct lruvec into struct book Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 02/15] mm: memory bookkeeping core Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 03/15] mm: add book->pages_count Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 04/15] mm: unify inactive_list_is_low() Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 05/15] mm: add book->reclaim_stat Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 06/15] mm: kill struct mem_cgroup_zone Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 07/15] mm: move page-to-book translation upper Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 08/15] mm: introduce book locking primitives Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 09/15] mm: handle book relocks on lumpy reclaim Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 10/15] mm: handle book relocks in compaction Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 11/15] mm: handle book relock in memory controller Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 12/15] mm: optimize books in update_page_reclaim_stat() Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 13/15] mm: optimize books in pagevec_lru_move_fn() Konstantin Khlebnikov
2012-02-15 22:57 ` [PATCH RFC 14/15] mm: optimize putback for 0-order reclaim Konstantin Khlebnikov
2012-02-15 22:58 ` [PATCH RFC 15/15] mm: split zone->lru_lock Konstantin Khlebnikov
2012-02-16  2:04 ` KAMEZAWA Hiroyuki [this message]
2012-02-16  5:43   ` [PATCH RFC 00/15] mm: memory book keeping and lru_lock splitting Konstantin Khlebnikov
2012-02-16  8:24     ` KAMEZAWA Hiroyuki
2012-02-16 11:02       ` Konstantin Khlebnikov
2012-02-16 15:54         ` Konstantin Khlebnikov
2012-02-16 23:54         ` KAMEZAWA Hiroyuki
2012-02-18  9:09           ` Konstantin Khlebnikov
2012-02-16  2:37 ` Hugh Dickins
2012-02-16  4:51   ` Konstantin Khlebnikov
2012-02-16 21:37     ` Hugh Dickins
2012-02-17 19:56       ` Konstantin Khlebnikov
2012-02-18  2:13       ` Hugh Dickins
2012-02-18  6:35         ` Konstantin Khlebnikov
2012-02-18  7:14           ` Hugh Dickins
2012-02-20  0:32             ` KAMEZAWA Hiroyuki

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