On 12/28/2017 12:15 PM, Nikolay Borisov wrote: > > On 23.12.2017 13:19, James Courtier-Dutton wrote: >> >> During a btrfs balance, the process hogs all CPU. >> Or, to be exact, any other program that wishes to use the SSD during a >> btrfs balance is blocked for long periods. Long periods being more >> than 5 seconds. >> Is there any way to multiplex SSD access while btrfs balance is >> operating, so that other applications can still access the SSD with >> relatively low latency? >> >> My guess is that btrfs is doing a transaction with a large number of >> SSD blocks at a time, and thus blocking other applications. >> >> This makes for atrocious user interactivity as well as applications >> failing because they cannot access the disk in a relatively low latent >> manner. >> For, example, this is causing a High Definition network CCTV >> application to fail. >> >> What I would really like, is for some way to limit SSD bandwidths to >> applications. >> For example the CCTV app always gets the bandwidth it needs, and all >> other applications can still access the SSD, but are rate limited. >> This would fix my particular problem. >> We have rate limiting for network applications, why not disk access also? > > So how are you running btrfs balance?
Or, to again take one step further back... *Why* are you running btrfs balance at all? :) > Are you using any filters > whatsoever? The documentation > [https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-balance] has the > following warning: > > Warning: running balance without filters will take a lot of time as it > basically rewrites the entire filesystem and needs to update all block > pointers. -- Hans van Kranenburg -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
