On 19 February 2011 00:25, Ivan Voras <ivo...@freebsd.org> wrote: > No such luck here; I've just tried an amd64 machine (8-STABLE from > today) in a new installation of XenServer 5.6 and while the GENERIC > kernel works stable enough, the XENHVM kernel produces all kinds of > timer-related problems, accompanied by messages like: > > Feb 18 23:20:03 xbsd kernel: calcru: runtime went backwards from > 28669021884109 usec to 22622950 usec for pid 11 (idle)
I've tried comparing the performance of GENERIC and XENHVM kernels on this machine with unixbench and it points to GENERIC being faster in everything - though I don't know if this is an artifact of bad timer behaviour (except for one test, more on this later). Here are the results: ==> unixbench-generic.txt <== TEST BASELINE RESULT INDEX Dhrystone 2 using register variables 116700.0 13828395.1 1185.0 Double-Precision Whetstone 55.0 4104.6 746.3 Execl Throughput 43.0 885.8 206.0 File Copy 1024 bufsize 2000 maxblocks 3960.0 142874.0 360.8 File Copy 256 bufsize 500 maxblocks 1655.0 65855.0 397.9 File Copy 4096 bufsize 8000 maxblocks 5800.0 146858.0 253.2 Pipe Throughput 12440.0 936158.7 752.5 Pipe-based Context Switching 4000.0 54004.1 135.0 Process Creation 126.0 1519.2 120.6 Shell Scripts (8 concurrent) 6.0 343.0 571.7 System Call Overhead 15000.0 578046.6 385.4 ==> unixbench-xenhvm.txt <== TEST BASELINE RESULT INDEX Dhrystone 2 using register variables 116700.0 13718470.5 1175.5 Double-Precision Whetstone 55.0 912662.7 165938.7 Execl Throughput 43.0 750.2 174.5 File Copy 1024 bufsize 2000 maxblocks 3960.0 96273.0 243.1 File Copy 256 bufsize 500 maxblocks 1655.0 79155.0 478.3 File Copy 4096 bufsize 8000 maxblocks 5800.0 91023.0 156.9 Pipe Throughput 12440.0 872682.9 701.5 Pipe-based Context Switching 4000.0 50348.4 125.9 Process Creation 126.0 1511.7 120.0 Shell Scripts (8 concurrent) 6.0 225.9 376.5 System Call Overhead 15000.0 561000.3 374.0 Only in the whetstone test (and consistently only in this one across multiple runs) is the test timing very visibly screwed up, which is obvious if observing test execution: it takes orders of magnitude longer than it should (hours) and produces order of magnitude "better" results than it should. It skews the "final score" so its unusable. Whetstone is FPU-intensive, unique among these tests. Just for comparison, here are the results on bare hardware, same OS & base hardware (MBO, CPU, RAM), different drives & number of CPUs: TEST BASELINE RESULT INDEX Dhrystone 2 using register variables 116700.0 15419836.3 1321.3 Double-Precision Whetstone 55.0 3566.9 648.5 Execl Throughput 43.0 2512.4 584.3 Pipe Throughput 12440.0 1079209.1 867.5 Pipe-based Context Switching 4000.0 94001.1 235.0 Process Creation 126.0 4752.0 377.1 System Call Overhead 15000.0 676244.5 450.8 The result of whetstone indicates that even the GENERIC kernel might have similar timer problems. _______________________________________________ freebsd-xen@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-xen To unsubscribe, send any mail to "freebsd-xen-unsubscr...@freebsd.org"