From: Kautuk Consul <consul.kautuk@gmail.com>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Joe Perches <joe@perches.com>,
Minchan Kim <minchan.kim@gmail.com>,
David Vrabel <david.vrabel@citrix.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] vmalloc: purge_fragmented_blocks: Acquire spinlock before reading vmap_block
Date: Thu, 8 Dec 2011 12:56:22 +0530 [thread overview]
Message-ID: <CAFPAmTSKXCiXNnFK0zR651ONju+ZBYE0qWUhCF9GXZRy=ieSJw@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1112072314140.28419@chino.kir.corp.google.com>
>
> That's intentional as an optimization, we don't care if
> vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS
> would speculatively be true after we grab vb->lock, we'll have to purge it
> next time instead. We certainly don't want to grab vb->lock for blocks
> that aren't candidates, so this optimization is a singificant speedup.
Ah, I agree.
Anyway, the probability of there being too many vmap_blocks being
missed due to concurrent changes
is not quite high, so I guess its okay that a few vmap_blocks get
purged next time.
Thanks.
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prev parent reply other threads:[~2011-12-08 7:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-08 7:02 Kautuk Consul
2011-12-08 7:07 ` David Rientjes
2011-12-08 7:13 ` Kautuk Consul
2011-12-08 7:18 ` David Rientjes
2011-12-08 7:26 ` Kautuk Consul [this message]
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