[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20100308113711.d7a249da.kamezawa.hiroyu@jp.fujitsu.com>
Date: Mon, 8 Mar 2010 11:37:11 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Cc: Andrea Righi <arighi@...eler.com>,
Balbir Singh <balbir@...ux.vnet.ibm.com>,
Vivek Goyal <vgoyal@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Trond Myklebust <trond.myklebust@....uio.no>,
Suleiman Souhlal <suleiman@...gle.com>,
Greg Thelen <gthelen@...gle.com>,
"Kirill A. Shutemov" <kirill@...temov.name>,
Andrew Morton <akpm@...ux-foundation.org>,
containers@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting
infrastructure
On Mon, 8 Mar 2010 11:17:24 +0900
Daisuke Nishimura <nishimura@....nes.nec.co.jp> wrote:
> > But IIRC, clear_writeback is done under treelock.... No ?
> >
> The place where NR_WRITEBACK is updated is out of tree_lock.
>
> 1311 int test_clear_page_writeback(struct page *page)
> 1312 {
> 1313 struct address_space *mapping = page_mapping(page);
> 1314 int ret;
> 1315
> 1316 if (mapping) {
> 1317 struct backing_dev_info *bdi = mapping->backing_dev_info;
> 1318 unsigned long flags;
> 1319
> 1320 spin_lock_irqsave(&mapping->tree_lock, flags);
> 1321 ret = TestClearPageWriteback(page);
> 1322 if (ret) {
> 1323 radix_tree_tag_clear(&mapping->page_tree,
> 1324 page_index(page),
> 1325 PAGECACHE_TAG_WRITEBACK);
> 1326 if (bdi_cap_account_writeback(bdi)) {
> 1327 __dec_bdi_stat(bdi, BDI_WRITEBACK);
> 1328 __bdi_writeout_inc(bdi);
> 1329 }
> 1330 }
> 1331 spin_unlock_irqrestore(&mapping->tree_lock, flags);
> 1332 } else {
> 1333 ret = TestClearPageWriteback(page);
> 1334 }
> 1335 if (ret)
> 1336 dec_zone_page_state(page, NR_WRITEBACK);
> 1337 return ret;
> 1338 }
We can move this up to under tree_lock. Considering memcg, all our target has "mapping".
If we newly account bounce-buffers (for NILFS, FUSE, etc..), which has no ->mapping,
we need much more complex new charge/uncharge theory.
But yes, adding new lock scheme seems complicated. (Sorry Andrea.)
My concerns is performance. We may need somehing new re-implementation of
locks/migrate/charge/uncharge.
Thanks,
-Kame
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists