Re: [PATCH 2/2] mm: compaction: Minimise the time IRQs aredisabled while isolating pages for migration

From: Andrea Arcangeli
Date: Mon Feb 28 2011 - 00:49:47 EST


On Mon, Feb 28, 2011 at 11:17:46AM +0900, KAMEZAWA Hiroyuki wrote:
> BTW, I forget why we always take zone->lru_lock with IRQ disabled....

To decrease lock contention in SMP to deliver overall better
performance (not sure how much it helps though). It was supposed to be
hold for a very short time (PAGEVEC_SIZE) to avoid giving irq latency
problems.
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