> From: Bob Friesenhahn [mailto:bfrie...@simple.dallas.tx.us] > > On Sat, 8 May 2010, Edward Ned Harvey wrote: > > > > A vast majority of the time, the opposite is true. Most of the time, > having > > swap available increases performance. Because the kernel is able to > choose: > > "Should I swap out this idle process, or should I dump files out of > cache?" > > With swap enabled, the kernel is given another degree of freedom, to > choose > > which is colder: idle process memory, or cold cached files. > > Are you sure about this? It is always good to be sure ...
This is the easiest way I know to show this in Linux: After the machine has been on, and doing things for a while (maybe hours, maybe days) run top or free. It is natural for the "free" to decrease to near-zero, while the buffers and cached climb to huge numbers. The buffers and cache are memory allocated to the kernel. It is also normal to see plenty of free, plenty of buffers and cache, and then see the swap usage increase to something nonzero. This is evidence that the Linux kernel is sometimes choosing to swap out idle processes, instead of dropping the buffers or cache usage. I don't really know how to do the same in solaris/opensolaris, but I haven't tried either. I only know that top doesn't show the same info in solaris 10. And then I moved on. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
