isnt' there a bigmem kernel for situations just like these?
On 8/9/07, Muli Ben-Yehuda <[EMAIL PROTECTED]> wrote: > On Thu, Aug 09, 2007 at 02:59:02PM +0300, Ira Abramov wrote: > > Quoting Muli Ben-Yehuda, from the post of Thu, 09 Aug: > > > > > > Because some PCI devices cannot deal with addresses over 4G. To be > > > able to map the RAM that has physical address over 4G in the CPU's > > > page tables, you need a PAE kernel. As for the penalty on speed, I > > > doubt you'll be able to measure it, and it will be offset by the extra > > > RAM. > > > > According to Marc (who is a man I don't like to disagree with) it's > > a hit of 3-5% on average on grid machines if I recall. > > I would like to understand this better, if you or Marc could shed more > details? In general, I believe you know what they say about "lies, > damn lies, and performance numbers". See some numbers from Ingo Molnar > which give the PAE overhead at a round 0.0% here: > http://kerneltrap.org/node/2891. YMMV. > > 100Hz 100.00% > 100Hz + PAE: 0.00% > > 1000Hz: -1.08% > 1000Hz + PAE: -1.08% > > Cheers, > Muli > > ================================================================= > To unsubscribe, send mail to [EMAIL PROTECTED] with > the word "unsubscribe" in the message body, e.g., run the command > echo unsubscribe | mail [EMAIL PROTECTED] > > ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
