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Date: Tue, 24 Jan 2012 17:45:28 -0800 From: Arun Sharma <asharma@...com> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> CC: <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>, Balbir Singh <bsingharora@...il.com>, <akpm@...ux-foundation.org> Subject: Re: [PATCH] mm: Enable MAP_UNINITIALIZED for archs with mmu On 1/23/12 7:07 PM, KAMEZAWA Hiroyuki wrote: > You can see reduction of clear_page() cost by removing GFP_ZERO but > what's your application's total performance ? Is it good enough considering > many risks ? I see 90k calls/sec to clear_page_c when running our application. I don't have data on the impact of GFP_ZERO alone, but an earlier experiment when we tuned malloc to not call madvise(MADV_DONTNEED) aggressively saved us 3% CPU. So I'm expecting this to be a 1-2% win. But not calling madvise() increases our RSS and increases the risk of OOM. Agree with your analysis that removing the cache misses at clear_page() is not always a win, since it moves the misses to the code where the app first touches the data. -Arun -- 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/
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