Please find my reply inlined.
On Wed, Aug 10, 2011 at 1:04 PM, Prateek Sharma <prateek3.14@xxxxxxxxx> wrote:
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 ?
On Wed, Aug 10, 2011 at 12:56 PM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote:
Hi///
> Thanks for replyingquite predictable.... during booting phase, your system read() much by
> Here is one observation worth mentioning.
> On boot system it shows Mapped < Cached (In fact much less)
doesn't mmap() that much....
by echoing "3" to drop_cache, you flush the content of page cache as
> 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.
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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