On Wed, Feb 06, 2013 at 03:12:13PM +0100, Seth wrote: > > On my workstation, and under the most extreme of loads I could think of, > > the most I've seen reported 'Dirty" is 11MiB. > (Note that it is usually solid 0M 90% of the time)
That's expected, and that's why I mentioned it's mostly useful for system administrators and advanced users. The Linux kernel, and in particular some recent versions, strongly limit the maximum dirty memory [1]. Tuning vm.dirty_background_ratio and vm.dirty_ratio is the most common way to optimize systems with high I/O load. For example, try setting them to respectively 25 and 75, do something that generates many I/O requests, such as unpacking a large archive (e.g. a linux tarball), and observe it on htop. You should also note that the rest of your system should be smoother than with the defaults (depending on your version; 2.6.38 already adds a lot in that regard, but older kernels may simply block hard on I/Os until they're finished). You should now see how users who care about memory and I/O can find it very useful. Compare that with the current separation of buffers and cache. A lot of users just don't understand what the difference between buffers and cache is, and can't make any useful decision based on that. I personally don't get the point of statistics that don't help understanding the work load and how to improve it. In addition, the default life time of dirty pages in the kernel is 30 seconds, which isn't that volatile. Think of a database server highly loaded with I/O requests, the meter will just never be 0. -- Richard Braun [1] http://www.gossamer-threads.com/lists/linux/kernel/1017204 ------------------------------------------------------------------------------ Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb _______________________________________________ htop-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/htop-general
