From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18411.3504.486805.813472@cargo.ozlabs.ibm.com> Date: Thu, 27 Mar 2008 14:00:00 +1100 From: Paul Mackerras Subject: Re: larger default page sizes... In-Reply-To: References: <20080321.145712.198736315.davem@davemloft.net> <20080324.133722.38645342.davem@davemloft.net> <18408.29107.709577.374424@cargo.ozlabs.ibm.com> <87wsnrgg9q.fsf@basil.nowhere.org> <18409.56843.909298.717089@cargo.ozlabs.ibm.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Andi Kleen , David Miller , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, torvalds@linux-foundation.org List-ID: Christoph Lameter writes: > One should emphasize that this test was a kernel compile which is not > a load that gains much from larger pages. 4k pages are mostly okay for > loads that use large amounts of small files. It's also worth emphasizing that 1.5% of the total time, or 21% of the system time, is pure software overhead in the Linux kernel that has nothing to do with the TLB or with gcc's memory access patterns. That's the cost of handling memory in small (i.e. 4kB) chunks inside the generic Linux VM code, rather than bigger chunks. Paul. -- 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