Re: [PATCH -mmotm 1/5] memcg: disable irq at page cgroup lock

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, 18 Mar 2010 09:49:44 +0530
Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote:

> * KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> [2010-03-18 08:54:11]:
> 
> > On Wed, 17 Mar 2010 17:28:55 +0530
> > Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote:
> > 
> > > * Andrea Righi <arighi@xxxxxxxxxxx> [2010-03-15 00:26:38]:
> > > 
> > > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > > > 
> > > > Now, file-mapped is maintaiend. But more generic update function
> > > > will be needed for dirty page accounting.
> > > > 
> > > > For accountig page status, we have to guarantee lock_page_cgroup()
> > > > will be never called under tree_lock held.
> > > > To guarantee that, we use trylock at updating status.
> > > > By this, we do fuzzy accounting, but in almost all case, it's correct.
> > > >
> > > 
> > > I don't like this at all, but in almost all cases is not acceptable
> > > for statistics, since decisions will be made on them and having them
> > > incorrect is really bad. Could we do a form of deferred statistics and
> > > fix this.
> > > 
> > 
> > plz show your implementation which has no performance regresssion.
> > For me, I don't neee file_mapped accounting, at all. If we can remove that,
> > we can add simple migration lock.
> 
> That doesn't matter, if you need it, I think the larger user base
> matters. Unmapped and mapped page cache is critical and I use it
> almost daily.
> 
> > file_mapped is a feattue you added. please improve it.
> >
> 
> I will, but please don't break it silently
> 
Andrea, could you go in following way ?

	- don't touch FILE_MAPPED stuff.
	- add new functions for other dirty accounting stuff as in this series.
	  (using trylock is ok.)
	
Then, no probelm. It's ok to add mem_cgroup_udpate_stat() indpendent from
mem_cgroup_update_file_mapped(). The look may be messy but it's not your
fault. But please write "why add new function" to patch description.

I'm sorry for wasting your time.

Thanks,
-Kame




--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>

[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]