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Date: Tue, 23 Jul 2024 17:09:13 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>, jpoimboe@kernel.org,
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 willy@infradead.org, vbabka@suse.cz, ziy@nvidia.com,
 linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v4] vmstat: Kernel stack usage histogram
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On Fri, 19 Jul 2024 15:04:40 -0700 Shakeel Butt <shakeel.butt@linux.dev> wrote:

> > > Any specific reason to add this function in header?
> > 
> > For performance reasons to keep it inlined into stack_not_used() which
> > is also defined as inline function in this header.
> > 
> 
> Is this really that performance critical?

Nope.  stack_not_used() is for CONFIG_DEBUG_STACK_USAGE and
stack_not_used() is slow.

I suggest that stack_not_used() (and hence kstack_histogram()) be
uninlined.  This can be a followup patch.