Hi, Please find my reply inlined.
On Wed, Aug 10, 2011 at 1:04 PM, Prateek Sharma <[email protected]>wrote: > > > On Wed, Aug 10, 2011 at 12:56 PM, Mulyadi Santosa < > [email protected]> wrote: > >> Hi/// >> >> On 09/08/2011, =/_00/\/\ <[email protected]> wrote: >> > Hi, >> > >> > Thanks for replying >> > Here is one observation worth mentioning. >> > On boot system it shows Mapped < Cached (In fact much less) >> >> quite predictable.... during booting phase, your system read() much by >> doesn't mmap() that much.... >> >> > After using system for some time following commands are executed. >> > # sync and echo 3 > /proc/sys/vm/drop_cache >> > >> > Whenever above command is executed I can see Mapped > Cached. >> >> by echoing "3" to drop_cache, you flush the content of page cache as >> much as possible ... >> >> > Here is my understanding of what drop_page_cache does: > All page-cache pages are 'dropped' except the following: > 1. Dirty pages. (they are *not* synced) > 2. Mapped pages (pages 'in use' , mapped by rmap ) > (There are a few more exceptions i dont recall now.) > But even in this case Cached (/proc/meminfo) should be always greater than Mapped(/proc/meminfo) (As it will contain mapped + Unmapped pages) I also saw that Cached (/proc/meminfo) does not include Buffer Cache. ========= fs/proc/meminfo.c ======== cached = global_page_state(NR_FILE_PAGES) - total_swapcache_pages - i.bufferram; ============================== Even if drop_cache is not done is it ever possible to get Cached < Mapped ? Regards, ~/
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