From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jack Steiner Date: Thu, 03 Nov 2005 03:55:07 +0000 Subject: Re: [RFC] 4-level page table directories. Message-Id: <20051103035506.GA8611@sgi.com> List-Id: References: <20051027041709.GA13193@attica.americas.sgi.com> In-Reply-To: <20051027041709.GA13193@attica.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Thu, Nov 03, 2005 at 02:36:18AM +0100, Gerald Pfeifer wrote: > On Thu, 3 Nov 2005, Ian Wienand wrote: > > On Wed, Nov 02, 2005 at 11:16:11AM -0600, Robin Holt wrote: > > I must admit to be a bit perplexed however. I would have thought that > > a customer who just spent (what I assume is a lot of) money on a > > machine to map huge areas of contiguous memory would really want to > > evaluate the probable benefits of larger pages, despite what Redhat > > ships. > > I'll note that SUSE has been shipping a 64k-pagesize kernel for more > than a year now as part of SUSE LINUX Enterprise Server 9, and I have > not seen a single L3 support call for this kernel. > > Which means that it's either completely bug free, or nobody uses it > in production. ;-) You are probably correct that very few sites use it. Part of the reason is that the 64k-pagesize kernel is built with NR_CPUS8 - not 512. I suspect that many of the big-memory sites have more than 128p. That makes the 64K page kernel unusable for those sites. In addition, the 64k-pagesize kernel does not have KDB configured. That makes support more difficult. Many sites use the "arch-kdb" commands to take quick dumps after system failures. (and of course it really is bug free :-) > > > I'm probably just extremley naive as to what customers really > > want, however. > > The reason customers generally prefer to go with default kernels, > as far as I can tell, is software certification. If you're only > running your special applications, you may not care, but for such > huge memory configs a DBMS like Oracle or DB2 is often part of the > picture, for example. True... > > Gerald > - > To unsubscribe from this list: send the line "unsubscribe linux-ia64" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Thanks .Jack Steiner (steiner@sgi.com) 651-683-5302 Principal Engineer SGI - Silicon Graphics, Inc.