I wholeheartedly agree. Of course, getting something other than CFQ as the default I/O scheduler is going to be a difficult task. Enough people upstream are convinced that we all NEED I/O priorities, when most of what I see people doing with them is bandwidth provisioning, which can be done much more accurately (and flexibly) using cgroups. Ironically, there have been a lot of in-kernel defaults that I have run into issues with recently, most of which originated in the DOS era, where a few MB of RAM was high-end. On 2014-09-02 08:55, Zack Coffey wrote: > While I'm sure some of those settings were selected with good reason, > maybe there can be a few options (2 or 3) that have some basic > intelligence at creation to pick a more sane option. > > Some checks to see if an option or two might be better suited for the > fs. Like the RAID5 stripe size. Leave the default as is, but maybe a > quick speed test to automatically choose from a handful of the most > common values. If they fail or nothing better is found, then apply the > default value just like it would now. > > > On Mon, Sep 1, 2014 at 9:22 PM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: >> On Tue, Sep 02, 2014 at 10:08:22AM +1000, Dave Chinner wrote: >>> Pretty obvious difference: avgrq-sz. btrfs is doing 512k IOs, ext4 >>> and XFS are doing is doing 128k IOs because that's the default block >>> device readahead size. 'blockdev --setra 1024 /dev/sdd' before >>> mounting the filesystem will probably fix it. >> >> Btw, it's really getting time to make Linux storage fs work out the >> box. There's way to many things that are stupid by default and we >> require everyone to fix up manually: >> >> - the ridiculously low max_sectors default >> - the very small max readahead size >> - replacing cfq with deadline (or noop) >> - the too small RAID5 stripe cache size >> >> and probably a few I forgot about. It's time to make things perform >> well out of the box.. >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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