From: Keith Busch <keith.busch@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Kirill Shutemov <kirill.shutemov@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH 1/6] mm/gup_benchmark: Time put_page
Date: Wed, 10 Oct 2018 16:28:43 -0600 [thread overview]
Message-ID: <20181010222843.GA11034@localhost.localdomain> (raw)
In-Reply-To: <20181010152655.8510270e5db753f6666f12d3@linux-foundation.org>
On Wed, Oct 10, 2018 at 03:26:55PM -0700, Andrew Morton wrote:
> On Wed, 10 Oct 2018 13:56:00 -0600 Keith Busch <keith.busch@intel.com> wrote:
>
> > We'd like to measure time to unpin user pages, so this adds a second
> > benchmark timer on put_page, separate from get_page.
> >
> > Adding the field will breaks this ioctl ABI, but should be okay since
> > this an in-tree kernel selftest.
> >
> > ...
> >
> > --- a/mm/gup_benchmark.c
> > +++ b/mm/gup_benchmark.c
> > @@ -8,7 +8,8 @@
> > #define GUP_FAST_BENCHMARK _IOWR('g', 1, struct gup_benchmark)
> >
> > struct gup_benchmark {
> > - __u64 delta_usec;
> > + __u64 get_delta_usec;
> > + __u64 put_delta_usec;
> > __u64 addr;
> > __u64 size;
> > __u32 nr_pages_per_call;
>
> If we move put_delta_usec to the end of this struct, the ABI remains
> back-compatible?
If the kernel writes to a new value appended to the end of the struct,
and the application allocated the older sized struct, wouldn't that
corrupt the user memory?
next prev parent reply other threads:[~2018-10-10 22:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 19:56 [PATCH 1/6] mm/gup_benchmark: Time put_page Keith Busch
2018-10-10 19:56 ` [PATCH 2/6] mm/gup_benchmark: Add additional pinning methods Keith Busch
2018-10-10 19:56 ` [PATCH 3/6] tools/gup_benchmark: Fix 'write' flag usage Keith Busch
2018-10-10 19:56 ` [PATCH 4/6] tools/gup_benchmark: Allow user specified file Keith Busch
2018-10-10 22:31 ` Andrew Morton
2018-10-10 22:42 ` Keith Busch
2018-10-10 19:56 ` [PATCH 5/6] tools/gup_benchmark: Add MAP_SHARED option Keith Busch
2018-10-10 19:56 ` [PATCH 6/6] tools/gup_benchmark: Add MAP_HUGETLB option Keith Busch
2018-10-10 22:26 ` [PATCH 1/6] mm/gup_benchmark: Time put_page Andrew Morton
2018-10-10 22:28 ` Keith Busch [this message]
2018-10-10 22:41 ` Andrew Morton
2018-10-10 22:40 ` Keith Busch
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181010222843.GA11034@localhost.localdomain \
--to=keith.busch@intel.com \
--cc=akpm@linux-foundation.org \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@intel.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.