(2013/03/13 15:58), Sha Zhengju wrote:
On Wed, Mar 6, 2013 at 6:59 PM, Kamezawa Hiroyuki
<kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
(2013/03/06 19:52), Glauber Costa wrote:
On 03/06/2013 02:45 PM, Kamezawa Hiroyuki wrote:
(2013/03/06 17:30), Glauber Costa wrote:
On 03/06/2013 04:27 AM, Kamezawa Hiroyuki wrote:
(2013/03/05 22:10), Glauber Costa wrote:
+ case _MEMSWAP: {
+ struct sysinfo i;
+ si_swapinfo(&i);
+
+ return ((memcg_read_root_rss() +
+ atomic_long_read(&vm_stat[NR_FILE_PAGES])) << PAGE_SHIFT) +
+ i.totalswap - i.freeswap;
How swapcache is handled ? ...and How kmem works with this calc ?
I am ignoring kmem, because we don't account kmem for the root cgroup
anyway.
Setting the limit is invalid, and we don't account until the limit is
set. Then it will be 0, always.
For swapcache, I am hoping that totalswap - freeswap will cover
everything swap related. If you think I am wrong, please enlighten me.
i.totalswap - i.freeswap = # of used swap entries.
SwapCache can be rss and used swap entry at the same time.
Well, yes, but the rss entries would be accounted for in get_mm_rss(),
won't they ?
What am I missing ?
I think the correct caluculation is
Sum of all RSS + All file caches + (i.total_swap - i.freeswap - # of mapped SwapCache)
In the patch, mapped SwapCache is counted as both of rss and swap.
After a quick look, swapcache is counted as file pages and meanwhile
use a swap entry at the same time(__add_to{delete_from}_swap_cache()).
Even though, I think we still do not need to exclude swapcache out,
because it indeed uses two copy of resource: one is swap entry, one is
cache, so the usage should count both of them in.
What I think it matters is that swapcache may be counted as both file
pages and rss(if it's a process's anonymous page), which we need to
subtract # of swapcache to avoid double-counting. But it isn't always
so: a shmem/tmpfs page may use swapcache and be counted as file pages
but not a rss, then we can not subtract swapcache... Is there anything
I lost?
Please don't think difficult. All pages for user/caches are counted in
LRU. All swap-entry usage can be cauht by total_swap_pages - nr_swap_pages.
We just need to subtract number of swap-cache which is double counted
as swap-entry and a page in LRU.
NR_ACTIVE_ANON + NR_INACTIVE_ANON + NR_ACTIVE_FILE + NR_INACTIVE_FILE
+ NR_UNEVICTABLE + total_swap_pages - nr_swap_pages - NR_SWAP_CACHE
is the number we whant for memsw.usage_in_bytes.
Thanks,
-Kame
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