linux-kernel - Re: [PATCH v6 06/19] mm: memcg/slab: obj

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Message-ID: <20200619225243.GB237539@carbon.dhcp.thefacebook.com>
Date:   Fri, 19 Jun 2020 15:52:43 -0700
From:   Roman Gushchin <guro@...com>
To:     Shakeel Butt <shakeelb@...gle.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Linux MM <linux-mm@...ck.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Kernel Team <kernel-team@...com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 06/19] mm: memcg/slab: obj_cgroup API

On Fri, Jun 19, 2020 at 03:16:44PM -0700, Shakeel Butt wrote:
> On Fri, Jun 19, 2020 at 2:38 PM Roman Gushchin <guro@...com> wrote:
> >
> [snip]
> > > > memcg->objcg is rcu protected.
> > > > objcg->memcg is a raw pointer, which is always pointing at a memory
> > > > cgroup, but can be atomically swapped to the parent memory cgroup. So
> > > > the caller
> > >
> > > What type of caller? The allocator?
> >
> > Basically whoever uses the pointer. Is it better to s/caller/user?
> >
> 
> Yes 'user' feels better.
> 
> > >
> [...]
> > >
> > > The normal stock can go to 32*nr_cpus*PAGE_SIZE. I am wondering if
> > > just PAGE_SIZE is too less for obj stock.
> >
> > It works on top of the current stock of 32 pages, so it can grab these
> > 32 pages without any atomic operations. And it should be easy to increase
> > this limit if we'll see any benefits.
> >
> > Thank you for looking into the patchset!
> >
> > Andrew, can you, please, squash the following fix based on Shakeel's suggestions?
> > Thanks!
> >
> > --
> 
> For the following squashed into the original patch:
> 
> Reviewed-by: Shakeel Butt <shakeelb@...gle.com>

Thank you!