From mboxrd@z Thu Jan 1 00:00:00 1970 From: Henning Rohlfs Subject: Re: Abysmal Performance Date: Tue, 21 Jun 2011 18:55:49 +0200 Message-ID: <49d786e216473ef3a83b62f5a46570bc@localhost> References: <7da312412980843ba746e4e8809060f8@localhost> <20110621080058.GA29265@attic.humilis.net> <4E00B646.4060109@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Cc: Henning Rohlfs , To: Josef Bacik Return-path: In-Reply-To: <4E00B646.4060109@redhat.com> List-ID: On Tue, 21 Jun 2011 11:18:30 -0400, Josef Bacik wrote: > On 06/21/2011 05:26 AM, Henning Rohlfs wrote: >> On Tue, 21 Jun 2011 10:00:59 +0200, Sander wrote: >>> Henning Rohlfs wrote (ao): >>>> - space_cache was enabled, but it seemed to make the problem >>>> worse. >>>> It's no longer in the mount options. >>> >>> space_cache is a one time mount option which enabled space_cache. >>> Not >>> supplying it anymore as a mount option has no effect (dmesg | grep >>> btrfs). >> >> I'm sure that after the first reboot after removing the flag from >> the >> mount options, the system was faster for a while. That must have >> been a >> coincidence (or just an error on my part). >> > > No, the space cache will make your system faster _after_ having been > enabled once. The reason for this is because we have to build the > cache > the slow way at first, and then after that we can do it the fast way. > What is probably happening is your box is slowing down trying to > build > this cache. Don't mount with clear_cache unless there is a bug in > your > cache. Let it do it's thing and stuff will get faster. I'm just reporting what I experienced. I had space_cache in the mount options while the problem developed and removed it when the system got too slow. After the next reboot the system was responsive for a short time (an hour maybe - which seems to have been unrelated to the mount option though from what you described). Now there's no difference whatsoever between no options, space_cache and clear_cache. To sum it up: I only played with the clear_cache option because the system got too slow in the first place. I don't see how the problem can be related to this option if changing it it makes no difference. Thanks, Henning