On Thu, 17 May 2012 14:10:49 +0200 Michal Hocko <mhocko@xxxxxxx> wrote: > > > This patch fixes a regression introduced by this commit for heavy shmem > > > > A performance regression, specifically. > > > > Are you able to quantify it? > > The customer's workload is shmem backed database (80% of RAM) and > they are measuring transactions/s with an IO in the background (20%). > Transactions touch more or less random rows in the table. > The rate goes down drastically when we start swapping out memory. > > Numbers are more descriptive (without the patch is 100%, with 5 > representative runs) > Average rate 315.83% > Best rate 131.76% > Worst rate 641.25% > > Standard deviation (calibrated to average) is ~4% while without the > patch we are at 62.82%. > The big variance without the patch is caused by the excessive swapping > which doesn't occur with the patch applied. > > * Worst run (100%) compared to a random run with the patch > pgpgin pswpin pswpout pgmajfault > 1.58% 0.00% 0.01% 0.22% > > Average size of the LRU lists: > nr_inactive_anon nr_active_anon nr_inactive_file nr_active_file > 52.91% 7234.72% 249.39% 126.64% > > * Best run > pgpgin pswpin pswpout pgmajfault > 3.37% 0.00% 0.11% 0.39% > > nr_inactive_anon nr_active_anon nr_inactive_file nr_active_file > 49.85% 3868.74% 175.03% 121.27% I turned the above into this soundbite: : The customer's workload is shmem backed database (80% of RAM) and they are : measuring transactions/s with an IO in the background (20%). Transactions : touch more or less random rows in the table. Total runtime was : approximately tripled by commit 64574746 and this patch restores the : previous throughput levels. Was that truthful? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>