Issue #884 has been updated by tuxillo. Description updated Category set to VM subsystem Status changed from New to In Progress Assignee deleted (0) Target version set to 3.8.0
Hi, I've done the same test under a vkernel: # sysctl vm.stats.vm.v_wire_count vm.stats.vm.v_wire_count: 11486 # dd if=/dev/zero of=./file bs=4m count=1 1+0 records in 1+0 records out 4194304 bytes transferred in 0.011742 secs (357201747 bytes/sec) # sysctl vm.stats.vm.v_wire_count vm.stats.vm.v_wire_count: 11675 # rm file # sysctl vm.stats.vm.v_wire_count vm.stats.vm.v_wire_count: 10647 And the same test on real hardware: antonioh@nas:~$ sysctl vm.stats.vm.v_wire_count vm.stats.vm.v_wire_count: 379492 antonioh@nas:~$ dd if=/dev/zero of=./file bs=4m count=1 1+0 records in 1+0 records out 4194304 bytes transferred in 0.035698 secs (117494297 bytes/sec) antonioh@nas:~$ sysctl vm.stats.vm.v_wire_count vm.stats.vm.v_wire_count: 379500 antonioh@nas:~$ rm file antonioh@nas:~$ sysctl vm.stats.vm.v_wire_count vm.stats.vm.v_wire_count: 378476 I don't see the high usage corecode showed in his test. Matt, there was a ton of work in the VM subsystem, is it possible that this is not the case anymore? Best regards, Antonio Huete ---------------------------------------- Bug #884: Performance/memory problems under filesystem IO load http://bugs.dragonflybsd.org/issues/884#change-11761 * Author: hasso * Status: In Progress * Priority: High * Assignee: * Category: VM subsystem * Target version: 3.8.0 ---------------------------------------- During testing drive with dd I noticed that there are serious performance problems. Programs which need disk access, block for 10 and more seconds. Sometimes they don't continue the work until dd is finished. Raw disk access (ie not writing to file, but directly to the disk) is reported to be OK (I can't test it myself). All tests are done with this command: dd if=/dev/zero of=./file bs=4096k count=1000 Syncing after each dd helps to reproduce it more reliably (cache?). There is one more strange thing in running these tests. I looked at memory stats in top before and after running dd. Before: Mem: 42M Active, 40M Inact, 95M Wired, 304K Cache, 53M Buf, 795M Free After: Mem: 70M Active, 679M Inact, 175M Wired, 47M Cache, 109M Buf, 1752K Free And as a side effect - I can't get my network interfaces up any more after running dd - "em0: Could not setup receive strucutres". -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://bugs.dragonflybsd.org/my/account
