Well I'm seeing that the CPU is taking a lot of time waiting for outstanding disk I/O request. Adi Adrian Chadd-3 wrote: > > Are you seeing high IO wait CPU use, or high IO wait times on IO? > > > > Adrian > > 2009/8/2 smaugadi <adi@xxxxxxxxxxxx>: >> >> Dear Adrian, >> Well my conclusion that this is an IO problem came from the fact that I >> see >> huge IO waits as the volume of traffic increase (with tools such as >> mpstat), >> when using ramdisk there is no such issue. >> I have configured the SSD drive with ext2, no journal, noatime. Used the >> “noop” I/O scheduler. >> In /etc/fstab >> /dev/sdb1 /cache ext2 defaults,noatime 1 2 >> >> hdparm results: >> hdparm -t /dev/sdb1 >> >> /dev/sdb1: >> Timing buffered disk reads: 304 MB in 3.01 seconds = 100.93 MB/sec >> ---- >> hdparm -T /dev/sdb1 >> >> /dev/sdb1: >> Timing cached reads: 4192 MB in 2.00 seconds = 2096.58 MB/sec >> >> Any ideas? >> >> Regards. >> >> >> >> Adrian Chadd-3 wrote: >>> >>> 2009/8/2 smaugadi <adi@xxxxxxxxxxxx>: >>>> >>>> Dear Adrian, >>>> During the implementation we encountered issues with all kind of >>>> variables >>>> such as: >>>> Limit of file descriptors (now the squid is using 204800). >>>> TCP port range was low (increased to 1024 65535) TCP timers (changed >>>> them) >>>> The ip_conntrack and hash size were low (now 524288 262144 >>>> respectively) >>>> >>>> Now we are at a point that IO is the only issue. >>> >>> What profiling have you done to support that? For example, one of the >>> issues I had which looked like IO performance was actually because the >>> controller was completely unhappy. Upgrading the firmware on the >>> controller card signficantly increased performance. >>> >>> But I think you need to post some further information about the >>> problem. "IO" can be rooted in a lot of issues. :) >>> >>> >>> Adrian >>> >>> >> >> -- >> View this message in context: >> http://www.nabble.com/Squid-high-bandwidth-IO-issue-%28ramdisk-SSD%29-tp24775448p24776193.html >> Sent from the Squid - Users mailing list archive at Nabble.com. >> >> > > -- View this message in context: http://www.nabble.com/Squid-high-bandwidth-IO-issue-%28ramdisk-SSD%29-tp24775448p24776478.html Sent from the Squid - Users mailing list archive at Nabble.com.
