On Mon, Jul 13, 2015 at 5:16 PM, Haribabu Kommi <kommi.harib...@gmail.com> wrote: > On Mon, Jul 13, 2015 at 12:06 PM, Haribabu Kommi > <kommi.harib...@gmail.com> wrote: >> On Thu, Jul 9, 2015 at 5:36 PM, Haribabu Kommi <kommi.harib...@gmail.com> >> wrote: >>> >>> I will do some performance tests and send you the results. >> >> Here are the performance results tested on my machine. >> >> >> Head vm patch vm+prefetch >> patch >> >> First vacuum 120sec <1sec <1sec >> second vacuum 180 sec 180 sec 30 sec >> >> I did some modifications in the code to skip the vacuum truncation by >> the first vacuum command. >> This way I collected the second vacuum time taken performance. >> >> I just combined your vm and prefetch patch into a single patch >> vm+prefetch patch without a GUC. >> I kept the prefetch as 32 and did the performance test. I chosen >> prefetch based on the current >> buffer access strategy, which is 32 for vacuum presently instead of an >> user option. >> Here I attached the modified patch with both vm+prefetch logic. >> >> I will do some tests on a machine with SSD and let you know the >> results. Based on these results, >> we can decide whether we need a GUC or not? based on the impact of >> prefetch on ssd machines. > > Following are the performance readings on a machine with SSD. > I increased the pgbench scale factor to 1000 in the test instead of 500 > to show a better performance numbers. > > Head vm patch vm+prefetch patch > > First vacuum 6.24 sec 2.91 sec 2.91 sec > second vacuum 6.66 sec 6.66 sec 7.19 sec > > There is a small performance impact on SSD with prefetch.
The above prefetch overhead is observed with prefeching of 1639345 pages. I feel this overhead is small. Hi Jeff, If you are fine with earlier attached patch, then I will mark this patch as ready for committer, to get some committer view on the patch. Regards, Hari Babu Fujitsu Australia -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers