On Mon, 05 Sep 2011 15:51:17 +0200 Swâmi Petaramesh <sw...@petaramesh.org> wrote:
> Hi list, > > I don't trust theoretical benchmarks that much and prefer "real-life > benchs" on the occasion, so here's mine: > > Given 4 laptops, the most powerful of which was running BTRFS and the > others ext3 or ext4, all machines running Ubuntu 11.04 Natty 32-bit with > a stock Ubuntu 2.6.38-11 kernel, all machines were given the following > FS-intensive task : > > - Upgrade O.S. from Ubuntu 11.04 Natty to 11.10 Oneiric (beta), using a > local packages apt-cacher. > > Machines : > > 1/ Acer Aspire 3104 WLMi, AMD Sempron Mobile 3500+ @1.8 GHz, 1.5 GB RAM, > 80 GB SATA HD, ext4 over standard partitions > > 2/ Asus EeePC 1005PE, Intel Atom N450 @1.66 GHz, 2 GB RAM, 250 GB SATA > HD, ext3 over AES-128 encrypted LVM > > 3/ Compaq Mini CQ10-740SF, Intel Atom N455 @1.66 GHz, 1 GB RAM, 250 GB > SATA HD, ext4 over standard partitions > > 4/ Dell XPS M1330, Intel Core 2 Duo T9300 @2.5 GHz, 2 GB RAM, 160 B SATA > HD, BTRFS over AES-128 encrypted LVM > > Results : > > All 3 ext3 / ext4 machines took between 60 and 90 minutes to complete > their upgrade. > > BTRFS machine took 20 HOURS so far, still counting (ETA 15 minutes left). > > Wow. Impressive. I've seen similar problem on Ubuntu-11 + Aspire One (8GB of slow "SSD"). More specifically half of ubuntu install went very fast and when disk was ~50% free things _suddenly_ gone slow. According to strace fsync() started to take ~10 seconds(!) and upper. It's not common filesystem behaviour, but a plain (and hard to catch?) bug. I don't have the box anymore. The root cause it to be found by some brave soul yet. I wonder if latencytop would get the profile of the issue. Maybe, btrfs degrades only after certain (insanely large?) amount of fsync() calls? -- Sergei
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