linux-kernel - Re: [PATCH] mm/cma: print total and used count in cma

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Message-Id: <20240926132534.8bd3acaf379ab592770e0d1b@linux-foundation.org>
Date: Thu, 26 Sep 2024 13:25:34 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Xiang Gao <gxxa03070307@...il.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, gaoxiang17
 <gaoxiang17@...omi.com>
Subject: Re: [PATCH] mm/cma: print total and used count in cma_alloc()

On Thu, 26 Sep 2024 20:00:49 +0800 Xiang Gao <gxxa03070307@...il.com> wrote:

> before:
> [   24.407814] cma: cma_alloc(cma (____ptrval____), name: reserved, count 1, align 0)
> [   24.413397] cma: cma_alloc(cma (____ptrval____), name: reserved, count 1, align 0)
> [   24.415886] cma: cma_alloc(cma (____ptrval____), name: reserved, count 1, align 0)
> 
> after:
> [   24.097989] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 64, request count 1, align 0)
> [   24.104260] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 65, request count 1, align 0)
> [   24.107504] cma: cma_alloc(cma (____ptrval____), name: reserved, total count 16384, used count: 66, request count 1, align 0)

OK, thanks.  We should explain why we're making this change!  The
previous version of the patch had "To better understand cma area during
debugging", but that isn't very specific.

Please tell us the use case - why is this information helpful?  How is
it used?