linux-kernel - Re: [PATCH v2 1/5] mm: memcg: don't call propagate_protected

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Message-ID: <yeic3imklc46iztcx2djt2ygxac57k7aeaaajkmp2vbfsd3gjr@ibfxai7ctndk>
Date: Wed, 24 Jul 2024 13:52:38 -0700
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, Johannes Weiner <hannes@...xchg.org>, 
	Michal Hocko <mhocko@...nel.org>, Muchun Song <muchun.song@...ux.dev>
Subject: Re: [PATCH v2 1/5] mm: memcg: don't call propagate_protected_usage()
 needlessly

On Wed, Jul 24, 2024 at 08:20:59PM GMT, Roman Gushchin wrote:
> Memory protection (min/low) requires a constant tracking of
> protected memory usage. propagate_protected_usage() is called
> on each page counters update and does a number of operations
> even in cases when the actual memory protection functionality
> is not supported (e.g. hugetlb cgroups or memcg swap counters).
> 
> It's obviously inefficient and leads to a waste of CPU cycles.
> It can be addressed by calling propagate_protected_usage() only
> for the counters which do support memory guarantees. As of now
> it's only memcg->memory - the unified memory memcg counter.
> 
> Signed-off-by: Roman Gushchin <roman.gushchin@...ux.dev>

Acked-by: Shakeel Butt <shakeel.butt@...ux.dev>