From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id AEFBB6B01EF for ; Mon, 5 Apr 2010 21:43:35 -0400 (EDT) Date: Mon, 5 Apr 2010 18:38:35 -0700 (PDT) From: Linus Torvalds Subject: Re: [PATCH 00 of 41] Transparent Hugepage Support #17 In-Reply-To: <20100406011345.GT5825@random.random> Message-ID: References: <20100405120906.0abe8e58.akpm@linux-foundation.org> <20100405193616.GA5125@elte.hu> <20100405232115.GM5825@random.random> <20100406011345.GT5825@random.random> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: Pekka Enberg , Ingo Molnar , Andrew Morton , linux-mm@kvack.org, Marcelo Tosatti , Adam Litke , Avi Kivity , Izik Eidus , Hugh Dickins , Nick Piggin , Rik van Riel , Mel Gorman , Dave Hansen , Benjamin Herrenschmidt , Mike Travis , KAMEZAWA Hiroyuki , Christoph Lameter , Chris Wright , bpicco@redhat.com, KOSAKI Motohiro , Balbir Singh , Arnd Bergmann , "Michael S. Tsirkin" , Peter Zijlstra , Johannes Weiner , Daisuke Nishimura List-ID: On Tue, 6 Apr 2010, Andrea Arcangeli wrote: > > In short I first measured the page fault improvement in host (~+50% > faster, sure that has nothing to do with pmd_huge or the tlb miss, I > said I mentioned it just for curiosity in fact), then measured the tlb > miss improvement in host (a few percent faster as usual with > hugetlbfs) then measured the boost in guest if host uses hugepages > (with no guest kernel change at all, just the tlb miss going faster in > guest and that boosts the guest kernel compile 6%) and then some other > test with dd with all combinations of host/guest using hugepages or > not, and also with dd run on bare metal with or without hugepages. Yeah, sorry. I misread your email - I noticed that 6% improvement for something that looked like a workload I might actually _care_ about, and didn't track the context enough to notice that it was just for the "host is using hugepages" case. So I thought it was a more interesting load than it was. The virtualization "TLB miss is expensive" load I can't find it in myself to care about. "Get a better CPU" is my answer to that one, Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org