From: Andrew Morton <akpm@linux-foundation.org>
To: Zhaoyang Huang <huangzhaoyang@gmail.com>
Cc: zhaoyang.huang@spreadtrum.com, Michal Hocko <mhocko@suse.com>,
Ingo Molnar <mingo@kernel.org>, zijun_hu <zijun_hu@htc.com>,
Vlastimil Babka <vbabka@suse.cz>,
Thomas Garnier <thgarnie@google.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
zijun_hu@zoho.com
Subject: Re: [PATCH] mm/vmalloc: add vm_struct for vm_map_ram area
Date: Wed, 19 Jul 2017 13:50:14 -0700 [thread overview]
Message-ID: <20170719135014.fdc882d1e28fd130104eff5d@linux-foundation.org> (raw)
In-Reply-To: <1500461043-7414-1-git-send-email-zhaoyang.huang@spreadtrum.com>
On Wed, 19 Jul 2017 18:44:03 +0800 Zhaoyang Huang <huangzhaoyang@gmail.com> wrote:
> /proc/vmallocinfo will not show the area allocated by vm_map_ram, which
> will make confusion when debug. Add vm_struct for them and show them in
> proc.
>
Please provide sample /proc/vmallocinfo so we can better understand the
proposal. Is there a means by which people can determine that a
particular area is from vm_map_ram()? I don't think so. Should there
be?
>
> ...
>
> @@ -1173,6 +1178,12 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t pro
> addr = (unsigned long)mem;
> } else {
> struct vmap_area *va;
> + struct vm_struct *area;
> +
> + area = kzalloc_node(sizeof(*area), GFP_KERNEL, node);
> + if (unlikely(!area))
> + return NULL;
Allocating a vm_struct for each vm_map_ram area is a cost. And we're
doing this purely for /proc/vmallocinfo. I think I'll need more
persuading to convince me that this is a good tradeoff, given that
*every* user will incur this cost, and approximately 0% of them will
ever use /proc/vmallocinfo.
So... do we *really* need this? If so, why?
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next prev parent reply other threads:[~2017-07-19 20:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-19 10:44 [PATCH] mm/vmalloc: add vm_struct for vm_map_ram area Zhaoyang Huang
2017-07-19 20:50 ` Andrew Morton [this message]
2017-07-20 1:15 ` Zhaoyang Huang
2017-07-20 1:20 ` Zhaoyang Huang
2017-07-20 2:36 ` zijun_hu
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