On Wed, Oct 22, 2008 at 04:31:43PM -0500, Nicolas Williams wrote: > On Wed, Oct 22, 2008 at 11:05:09PM +0200, Kees Nuyt wrote: > > Just a remark: > > Increasing the SQLite page_size while keeping the same > > [default_]cache_size will effectively increase the amount of memory > > allocated to the SQLite cache, because the SQLite cache_size is > > expressed in pages. > > IMHO, for a fair performance comparison, one should half the > > cache_size when the page_size is doubled. > > I'm not sure that I agree. While the cache gets larger if you increase > the page size, the cache nonetheless caches the same number of integral > pages. Each miss requires reading a whole page, and each addition to > the cache, when full, requires evicting another.
On second thought, making the sqlite cache thrash != thrashing the disk. The filesystem cache will still help -- there will be more data copies or VM page flips, but that's probably OK. I'll see how to make the default cache_size determination take the DB's page_size into account. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
