From: Chandan Rajendra <chandan@linux.vnet.ibm.com>
To: dsterba@suse.cz
Cc: David Sterba <dsterba@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs: allocate exact page array size in extent_buffer
Date: Fri, 15 Jul 2016 17:28:42 +0530 [thread overview]
Message-ID: <2207881.izrC6JhlLc@localhost.localdomain> (raw)
In-Reply-To: <20160715094406.GR10595@twin.jikos.cz>
On Friday, July 15, 2016 11:44:06 AM David Sterba wrote:
> On Fri, Jul 15, 2016 at 11:47:07AM +0530, Chandan Rajendra wrote:
> > On Thursday, July 14, 2016 02:29:32 PM David Sterba wrote:
> > > The calculation of extent_buffer::pages size was done for 4k PAGE_SIZE,
> > > but this wastes 15 unused pointers on arches with large page size. Eg.
> > > on ppc64 this gives 15 * 8 = 120 bytes.
> > >
> >
> > The non PAGE_SIZE aligned extent buffer usage in page straddling tests in
> > test_eb_bitmaps() need atleast one more page. So how about the following ...
> >
> > #define INLINE_EXTENT_BUFFER_PAGES (BTRFS_MAX_METADATA_BLOCKSIZE / PAGE_SIZE + 1)
>
> Could the extra page pointer be normally used? Ie. not just for the sake
> of the tests. I'd rather not waste the bytes. As a compromise, we can do +1
> only if the tests are compiled in.
>
I don't see any other scenario where the extra page pointer gets used. Also, I
just executed fstests with your patch applied and disabling self-tests from
the kernel configuration. The tests ran fine.
--
chandan
prev parent reply other threads:[~2016-07-15 11:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 12:29 [PATCH] btrfs: allocate exact page array size in extent_buffer David Sterba
2016-07-14 16:21 ` Chris Mason
2016-07-15 6:17 ` Chandan Rajendra
2016-07-15 9:44 ` David Sterba
2016-07-15 11:58 ` Chandan Rajendra [this message]
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