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Low Latency Happiness
Jun. 20th, 2010 12:44 pmAs I mentioned some time ago, I've been putting up with terrible GUI performance on my Linux box for about six months now. Every OS update has been making it worse, not better, until it got to the point last week that any non-trivial disk access (loading a 1 GB file, moving a file to another partition, etc) caused the UI to freeze: the mouse and text cursors wouldn't respond, it could take minutes to switch windows, and the like.
Two days ago I finally got fed up with this state of affairs and started Googling for possible causes and known fixes. It turns out there have been a lot of folks complaining about this and most of them have been running 64-bit kernels, like mine. As usual there were many things blamed and many suggested fixes one could try. I tried a few of the easier ones (tweaking the standard CFS cpu scheduler for example) without luck.
Many folks swore by the Zen kernel since it is tuned for low-latency desktop applications, plus includes a number of experimental schedulers that folks say give better performance. In particular it has the BFS CPU scheduler, the BFQ IO scheduler, and the SLQB Slab allocator which is supposed to help keep virtual pages in a state that makes for better swapping performance.
It was configuring and installing this kernel the other day that caused my computer to stop booting (for reasons that ultimately had nothing to do with the kernel) but once I had the problems sorted (incompatible versions of grub) and had booted into the new kernel I was surprised and delighted to see that I now had a responsive desktop again, even when performing heavy IO.
I can't say for sure which of the various tweaks did the job, or if it was a combination of all of the above, but I can say I am very happy to have a low latency user interface again.
Two days ago I finally got fed up with this state of affairs and started Googling for possible causes and known fixes. It turns out there have been a lot of folks complaining about this and most of them have been running 64-bit kernels, like mine. As usual there were many things blamed and many suggested fixes one could try. I tried a few of the easier ones (tweaking the standard CFS cpu scheduler for example) without luck.
Many folks swore by the Zen kernel since it is tuned for low-latency desktop applications, plus includes a number of experimental schedulers that folks say give better performance. In particular it has the BFS CPU scheduler, the BFQ IO scheduler, and the SLQB Slab allocator which is supposed to help keep virtual pages in a state that makes for better swapping performance.
It was configuring and installing this kernel the other day that caused my computer to stop booting (for reasons that ultimately had nothing to do with the kernel) but once I had the problems sorted (incompatible versions of grub) and had booted into the new kernel I was surprised and delighted to see that I now had a responsive desktop again, even when performing heavy IO.
I can't say for sure which of the various tweaks did the job, or if it was a combination of all of the above, but I can say I am very happy to have a low latency user interface again.
