From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mackerras Date: Tue, 25 Mar 2008 11:50:00 +0000 Subject: Re: larger default page sizes... Message-Id: <18408.59112.945786.488350@cargo.ozlabs.ibm.com> List-Id: References: <20080324.133722.38645342.davem@davemloft.net> <18408.29107.709577.374424@cargo.ozlabs.ibm.com> <20080324.211532.33163290.davem@davemloft.net> In-Reply-To: <20080324.211532.33163290.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Miller Cc: clameter@sgi.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, torvalds@linux-foundation.org David Miller writes: > From: Paul Mackerras > Date: Tue, 25 Mar 2008 14:29:55 +1100 > > > The performance advantage of using hardware 64k pages is pretty > > compelling, on a wide range of programs, and particularly on HPC apps. > > Please read the rest of my responses in this thread, you > can have your HPC cake and eat it too. It's not just HPC, as I pointed out, it's pretty much everything, including kernel compiles. And "use hugepages" is a pretty inadequate answer given the restrictions of hugepages and the difficulty of using them. How do I get gcc to use hugepages, for instance? Using 64k pages gives us a performance boost for almost everything without the user having to do anything. If the hugepage stuff was in a state where it enabled large pages to be used for mapping an existing program, where possible, without any changes to the executable, then I would agree with you. But it isn't, it's a long way from that, and (as I understand it) Linus has in the past opposed the suggestion that we should move in that direction. Paul.