From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from james.kirk.hungrycats.org ([174.142.39.145]:39206 "EHLO james.kirk.hungrycats.org" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751079AbaL0S2u (ORCPT ); Sat, 27 Dec 2014 13:28:50 -0500 Date: Sat, 27 Dec 2014 13:28:46 -0500 From: Zygo Blaxell To: Hugo Mills , Martin Steigerwald , Robert White , linux-btrfs@vger.kernel.org Subject: Re: BTRFS free space handling still needs more work: Hangs again Message-ID: <20141227182846.GA11878@hungrycats.org> References: <3738341.y7uRQFcLJH@merkaba> <549DE5C6.2000606@pobox.com> <4232026.31LFOYpm2s@merkaba> <20141227093043.GJ25267@carfax.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Kj7319i9nmIyA2yE" In-Reply-To: <20141227093043.GJ25267@carfax.org.uk> Sender: linux-btrfs-owner@vger.kernel.org List-ID: --Kj7319i9nmIyA2yE Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Sat, Dec 27, 2014 at 09:30:43AM +0000, Hugo Mills wrote: > On Sat, Dec 27, 2014 at 10:01:17AM +0100, Martin Steigerwald wrote: > > Am Freitag, 26. Dezember 2014, 14:48:38 schrieb Robert White: > > > On 12/26/2014 05:37 AM, Martin Steigerwald wrote: > Now, since you're seeing lockups when the space on your disks is > all allocated I'd say that's a bug. However, you're the *only* person > who's reported this as a regular occurrence. Does this happen with all > filesystems you have, or just this one? I do see something similar, but there are so many problems going on I have no idea which ones to report, and which ones are my own doing. :-P I see lots of CPU being burned when all the disk space is allocated to chunks, but there is still lots of space free (multiple GB) inside the chunks. iotop shows a crapton of disk writes (1-5MB/sec) from one kworker. There are maybe a few kB/sec of writes through the filesystem at the time. The filesystem where I see this most is on a laptop, so the disk writes also hit the CPU again for encryption. There's so much CPU usage it's worth mentioning twice. :-( 'watch cat /proc/12345/stack' on the active processes shows the kernel fairly often in that new chunk deallocator function whose name escapes me at the moment. Deleting a bunch of data then running balance helps return to sane CPU usage...for a while (maybe a week?). It's not technically "locked up" per se, but when a 5KB download takes a minute or more, most users won't wait around to see the difference. Kernel versions I'm using are 3.17.7 and 3.18.1. --Kj7319i9nmIyA2yE Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAlSe+l4ACgkQgfmLGlazG5zzNACghx7EGnU0vxuzvcn4hYGfnFFv hxcAn2UmJBUyRfcsqu0xQ6SqXSEJ/eSY =91Zq -----END PGP SIGNATURE----- --Kj7319i9nmIyA2yE--