From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giuseppe Scrivano Subject: Re: [PATCH] Btrfs: don't allocate more than max_available bytes when looped Date: Mon, 03 Aug 2009 22:53:37 +0200 Message-ID: <87prbc62lq.fsf@master.homenet> References: <87fxc9yhu8.fsf@master.homenet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: linux-btrfs@vger.kernel.org, Chris Mason Return-path: In-Reply-To: <87fxc9yhu8.fsf@master.homenet> (Giuseppe Scrivano's message of "Mon, 03 Aug 2009 00:24:47 +0200") List-ID: Hi Chris, Thanks for your comments, I changed the patch according to them. >>From my tests, I can see that it helps to get 10% more usable space on a 256MB partition and 5% on a 750MB one. Cheers, Giuseppe >>From 4eff62a7132018f8685cdeff3aa439089c708258 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Mon, 3 Aug 2009 22:26:43 +0200 Subject: [PATCH] Btrfs: reduce the default min_stripe_size The default min_stripe_size used by __btrfs_alloc_chunk was reduced to 32MB for data and 16MB for metadata chunks. Also, after a failed attempt to alloc data, try again reducing the minimum size by a factor of 4. It may help allocating space that wouldn't otherwise. --- fs/btrfs/volumes.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 5dbefd1..a39b651 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -2166,10 +2166,10 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans, if (type & BTRFS_BLOCK_GROUP_DATA) { max_chunk_size = 10 * calc_size; - min_stripe_size = 64 * 1024 * 1024; + min_stripe_size = 32 * 1024 * 1024; } else if (type & BTRFS_BLOCK_GROUP_METADATA) { max_chunk_size = 4 * calc_size; - min_stripe_size = 32 * 1024 * 1024; + min_stripe_size = 16 * 1024 * 1024; } else if (type & BTRFS_BLOCK_GROUP_SYSTEM) { calc_size = 8 * 1024 * 1024; max_chunk_size = calc_size * 2; @@ -2190,6 +2190,9 @@ again: map->num_stripes = num_stripes; } + if (looped) + min_stripe_size = min_stripe_size / 4; + if (calc_size * num_stripes > max_chunk_size) { calc_size = max_chunk_size; do_div(calc_size, num_stripes); -- 1.6.3.3