Messages in this thread | | | From | "Borzenkov, Andrey" <> | Date | Fri, 13 Jan 2012 06:20:23 +0100 | Subject | RE: Extermeley large PageTables over 500G on kernel 2.6.32.49 (SLES11 SP1) |
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> -----Original Message----- > From: Avi Kivity [mailto:avi@redhat.com] > Sent: Wednesday, January 11, 2012 3:27 PM > To: Borzenkov, Andrey > Cc: Eric Dumazet; linux-kernel@vger.kernel.org > Subject: Re: Extermeley large PageTables over 500G on kernel 2.6.32.49 > (SLES11 SP1) > > On 01/11/2012 12:52 PM, Borzenkov, Andrey wrote: > > > If not, its normal to eat so much memory for page tables > > > > > > grep VmPTE /proc/*/status > > > > > > > > > > Forgive my ignorance. I thought that > > > > 1. PTE is 8 bytes per page, which is 4K which gives 2K per 1M of memory > > 2. All processes sharing the same shared memory share the same page > table > > > > So page table for Oracle SGA 500G would be around 1G and shared by all > Oracle clients. Is my assumption incorrect? > > > > The second assumption is incorrect. So fully populated the 2000 > processes would consume 2T; they just haven't accessed all the SGA yet. >
Does kernel ever free allocated page tables, or once allocated they stick for the process lifetime?
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