linux-kernel - Re: [PATCH -V3 2/9] cacheinfo: calculate size of per-CPU data cache slice

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Message-ID: <20231019121115.mwm6eroigcrr6bi4@techsingularity.net>
Date:   Thu, 19 Oct 2023 13:11:15 +0100
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Huang Ying <ying.huang@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Arjan Van De Ven <arjan@...ux.intel.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        David Hildenbrand <david@...hat.com>,
        Johannes Weiner <jweiner@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Michal Hocko <mhocko@...e.com>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Matthew Wilcox <willy@...radead.org>,
        Christoph Lameter <cl@...ux.com>
Subject: Re: [PATCH -V3 2/9] cacheinfo: calculate size of per-CPU data cache
 slice

On Mon, Oct 16, 2023 at 01:29:55PM +0800, Huang Ying wrote:
> This can be used to estimate the size of the data cache slice that can
> be used by one CPU under ideal circumstances.  Both DATA caches and
> UNIFIED caches are used in calculation.  So, the users need to consider
> the impact of the code cache usage.
> 
> Because the cache inclusive/non-inclusive information isn't available
> now, we just use the size of the per-CPU slice of LLC to make the
> result more predictable across architectures.  This may be improved
> when more cache information is available in the future.
> 
> A brute-force algorithm to iterate all online CPUs is used to avoid
> to allocate an extra cpumask, especially in offline callback.
> 
> Signed-off-by: "Huang, Ying" <ying.huang@...el.com>

Acked-by: Mel Gorman <mgorman@...hsingularity.net>

-- 
Mel Gorman
SUSE Labs