linux-kernel - Re: [PATCH] lib: stackdepot: Add support to configure STACK_HASH

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Message-Id: <20201112145649.3fcd9dc4d6d3db4bd26245bb@linux-foundation.org>
Date:   Thu, 12 Nov 2020 14:56:49 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Vijayanand Jitta <vjitta@...eaurora.org>
Cc:     Minchan Kim <minchan@...nel.org>, linux-mm <linux-mm@...ck.org>,
        glider@...gle.com, Dan Williams <dan.j.williams@...el.com>,
        broonie@...nel.org, mhiramat@...nel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Yogesh Lal <ylal@...eaurora.org>,
        Vinayak Menon <vinmenon@...eaurora.org>
Subject: Re: [PATCH] lib: stackdepot: Add support to configure
 STACK_HASH_SIZE

On Thu, 12 Nov 2020 18:26:24 +0530 Vijayanand Jitta <vjitta@...eaurora.org> wrote:

> >> 1. page_owner=off, stackdepot_stack_hash=0 -> no more wasted memory
> >> when we don't use page_owner
> >> 2. page_owner=on, stackdepot_stack_hash=8M -> reasonable hash size
> >> when we use page_owner.
> >>
> >>
> > 
> > This idea looks fine to me. Andrew and others would like to hear your
> > comments as well on this before implementing.
> > 
> > Thanks,
> > Vijay
> > 
> 
> Awaiting for comments from Andrew and others.

I don't actually understand the problem.

What is it about page-owner that causes stackdepot to consume
additional memory?  As far as I can tell, sizeof(struct stack_record)
isn't affected by page-owner?