On Thu, May 28, 2009 at 12:50 PM, Fabrix <fabrixio1@xxxxxxxxx> wrote: > > HI. > > Someone had some experience of bad performance with postgres in some server > with many processors? Seems to depend on the processors and chipset a fair bit. > I have a server with 4 CPUS dual core and gives me a very good performance > but I have experienced problems with another server that has 8 CPUS quad > core (32 cores). The second one only gives me about 1.5 of performance of > the first one. What model CPUs and chipset on the mobo I wonder? > Monitoring (nmon, htop, vmstat) see that everything is fine (memory, HD, > eth, etc) except that processors regularly climb to 100%. > > I can see that the processes are waiting for CPU time: > > vmstat 1 > > procs -----------memory---------- ---swap-- -----io---- --system-- > -----cpu------ > r b swpd free buff cache si so bi bo in cs us sy id > wa st > 0 0 0 47123020 117320 17141932 0 0 8 416 1548 2189 1 1 > 99 0 0 > 0 0 0 47121904 117328 17141940 0 0 8 148 1428 2107 1 1 > 98 0 0 > 0 0 0 47123144 117336 17141956 0 0 8 172 1391 1930 1 0 > 99 0 0 > 0 0 0 47124756 117352 17141940 0 0 8 276 1327 2171 1 1 > 98 0 0 > 0 0 0 47118556 117360 17141956 0 0 0 100 1452 2254 1 1 > 98 0 0 > 2 0 0 47120364 117380 17141952 0 0 8 428 1526 2477 1 0 > 99 0 0 > 1 0 0 47119372 117388 17141972 0 0 0 452 1581 2662 1 1 > 98 0 0 > 0 0 0 47117948 117396 17141988 0 0 16 468 1705 3243 1 1 > 97 0 0 > 0 0 0 47116708 117404 17142020 0 0 0 268 1610 2115 1 1 > 99 0 0 > 0 0 0 47119688 117420 17142044 0 0 0 200 1545 1810 1 1 > 98 0 0 > 318 0 0 47116464 117440 17142052 0 0 0 532 1416 2396 1 0 > 99 0 0 > 500 0 0 47115224 117440 17142052 0 0 0 0 1118 322144 91 > 5 4 0 0 > 440 0 0 47114728 117440 17142044 0 0 0 0 1052 333137 90 > 5 5 0 0 > 339 0 0 47114484 117440 17142048 0 0 0 0 1061 337528 85 > 4 11 0 0 > 179 0 0 47114112 117440 17142048 0 0 0 0 1066 312873 71 > 4 25 0 0 > 5 1 0 47122180 117468 17142028 0 0 192 3128 1958 136804 23 > 2 75 1 0 > 3 0 0 47114264 117476 17142968 0 0 608 5828 2688 4684 7 2 > 89 2 0 > 0 1 0 47109940 117484 17142876 0 0 512 5084 2248 3727 3 1 > 94 2 0 > 0 1 0 47119692 117500 17143816 0 0 520 4976 2231 2941 2 1 > 95 2 0 > > > Have postgres problems of lock or degradation of performance with many > CPU's? > Any comments? Looks like a context switch storm, which was pretty common on older Xeon CPUs. I imagine with enough pg processes running on enough CPUs it could still be a problem. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
