(2012/04/25 23:29), Glauber Costa wrote: > On 04/24/2012 10:44 PM, KAMEZAWA Hiroyuki wrote: >> (2012/04/23 8:53), Glauber Costa wrote: >> >>> Some allocations need to be accounted to the root memcg regardless >>> of their context. One trivial example, is the allocations we do >>> during the memcg slab cache creation themselves. Strictly speaking, >>> they could go to the parent, but it is way easier to bill them to >>> the root cgroup. >>> >>> Only generic kmalloc allocations are allowed to be bypassed. >>> >>> The function is not exported, because drivers code should always >>> be accounted. >>> >>> This code is mosly written by Suleiman Souhlal. >>> >>> Signed-off-by: Glauber Costa<glommer@xxxxxxxxxxxxx> >>> CC: Christoph Lameter<cl@xxxxxxxxx> >>> CC: Pekka Enberg<penberg@xxxxxxxxxxxxxx> >>> CC: Michal Hocko<mhocko@xxxxxxx> >>> CC: Kamezawa Hiroyuki<kamezawa.hiroyu@xxxxxxxxxxxxxx> >>> CC: Johannes Weiner<hannes@xxxxxxxxxxx> >>> CC: Suleiman Souhlal<suleiman@xxxxxxxxxx> >> >> >> Seems reasonable. >> Reviewed-by: KAMEZAWA Hiroyuki<kamezawa.hiroyu@xxxxxxxxxxxxxx> >> >> Hmm...but can't we find the 'context' in automatic way ? >> > > Not that I can think of. Well, actually, not without adding some tests > to the allocation path I'd rather not (like testing for the return > address and then doing a table lookup, etc) > > An option would be to store it in the task_struct. So we would allocate > as following: > > memcg_skip_account_start(p); > do_a_bunch_of_allocations(); > memcg_skip_account_stop(p); > > The problem with that, is that it is quite easy to abuse. > but if we don't export that to modules, it would be acceptable. > > Question is, given the fact that the number of kmalloc_no_account() is > expected to be really small, is it worth it? > ok, but.... There was an idea __GFP_NOACCOUNT, which is better ? Are you afraid that__GFP_NOACCOUNT can be spread too much rather than kmalloc_no_account() ? Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
