From: Theodore Ts'o <tytso@mit.edu>
To: Andrey Sidorov <qrxd43@motorola.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: mke2fs with bigalloc is too slow
Date: Fri, 15 Mar 2013 10:28:44 -0400 [thread overview]
Message-ID: <20130315142844.GA7403@thunk.org> (raw)
In-Reply-To: <CAA0+VHx5=hYPOefnA-5eTrwFMtsg4sLujCLB91fGx2eoZrP0+w@mail.gmail.com>
On Fri, Mar 15, 2013 at 01:53:58AM +0400, Andrey Sidorov wrote:
>
> Oh, thanks for pointing that! I was mostly reading v1.42 that is more
> than year old and missed the fact 1.42.7 has rbtree bitmap
> implementation.
> That explains why formatting bigalloc became slower compared to 1.42.
> In this case ffs/ffz seem like a right choice, I'll try them. I'll
> also try mirroring as it won't waste much RAM and might be faster.
As you'll discover fairly quickly, we haven't implemented ffs/ffz for
rbtree bitmaps yet. We've implemented find_first_zero for for
bitarrays (and for the generic bitmap framework in lib/ext2fs/bitops.h
and lib/ext2fs/gen_bitmap*.c), but not in lib/ext2fs/blkmap64_rb.c
yet. More critically for the mke2fs's use case in
convert_subcluster_bitmap, will be the find_first_set operation.
Adding this has been on my todo list for a while, but I just haven't
had the time. Note that test cases for this will be critically
important, especially if we start using them in correctness-critical
code such as e2fsck.
- Ted
prev parent reply other threads:[~2013-03-15 14:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-13 16:04 mke2fs with bigalloc is too slow Andrey Sidorov
2013-03-13 19:00 ` Theodore Ts'o
2013-03-14 21:53 ` Andrey Sidorov
2013-03-15 14:28 ` Theodore Ts'o [this message]
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