----- Original Message -----
From: "Stefan `Sec` Zehl" <[email protected]>
On Thu, Mar 20, 2014 at 10:39 +0000, Jonathan Price wrote:
Sorry if this message duplicates in the list, but I just realised I
didn't reply to this conversation thread.
I sadly don't have an old enough copy of the server lying around, but I
did run a ktrace on the new server, and the dump can be found here:
https://gravitygunonly.com/ktrace.out
Does anybody know of a comparable kernel tracing tool for linux, so I
can do a rough comparison?
I got the server running in an Ubuntu VirtualBox on FreeBSD, and it
appears to run fine in there. I ran it under strace -ff (one file per
forked process) and put those up at http://tf2.42.org/strace/
When testing these things avoid VM's as thats will almost certainly
cause issues, VM's are bad for running games.
I notice from those traces it seems they may have switched from using
gettimeofday to clock_gettime with CLOCK_MONOTONIC and CLOCK_REALTIME
this could be the cause of increased delay on older versions of FreeBSD
when compared to Linux as the later exports said syscalls to userspace
so avoiding the kernel call overhead.
This was added in later versions of FreeBSD.
This can also be HW dependent so worth grabbing bench_clock_realtime and
testing.
Results I get here are:
== FreeBSD 8.3 ==
./bench_clock_realtime 1000000 | sort -rnk1
clock realtime micro-benchmark. 1000000 syscall iterations.
Avg. us/call Elapsed Name
1.295952 1.295952 clock_gettime(2/CLOCK_REALTIME)
1.288814 1.288814 gettimeofday(2)
1.268418 1.268418 clock_gettime(2/CLOCK_MONOTONIC)
0.227554 0.227554 time(3)
0.188536 0.188536 clock_gettime(2/CLOCK_MONOTONIC_FAST)
0.186711 0.186711 clock_gettime(2/CLOCK_REALTIME_FAST)
0.183949 0.183949 clock_gettime(2/CLOCK_SECOND)
Value from time(3): 1395397354
Last value from gettimeofday(2): 1395397353.841231 Equal: 0
Last value from clock_gettime(2/CLOCK_SECOND): 1395397355.000000000 Equal:
999999
Last value from clock_gettime(2/CLOCK_REALTIME_FAST): 1395397355.551175479
Equal: 999812
Last value from clock_gettime(2/CLOCK_REALTIME): 1395397355.364957273 Equal: 0
Last value from clock_gettime(2/CLOCK_MONOTONIC_FAST): 238087.092726098 Equal:
999810
Last value from clock_gettime(2/CLOCK_MONOTONIC): 238086.904221625 Equal: 0
== FreeBSD HEAD (11) ==
./bench_clock_realtime 1000000 | sort -rnk1
clock realtime micro-benchmark. 1000000 syscall iterations.
Avg. us/call Elapsed Name
0.072954 0.072954 time(3)
0.071690 0.071690 clock_gettime(2/CLOCK_REALTIME)
0.071656 0.071656 clock_gettime(2/CLOCK_REALTIME_FAST)
0.071273 0.071273 clock_gettime(2/CLOCK_SECOND)
0.070846 0.070846 clock_gettime(2/CLOCK_MONOTONIC)
0.070843 0.070843 clock_gettime(2/CLOCK_MONOTONIC_FAST)
0.070008 0.070008 gettimeofday(2)
Value from time(3): 1395397524
Last value from gettimeofday(2): 1395397524.787761 Equal: 930157
Last value from clock_gettime(2/CLOCK_SECOND): 1395397525.000000000 Equal:
999999
Last value from clock_gettime(2/CLOCK_REALTIME_FAST): 1395397525.004133405
Equal: 0
Last value from clock_gettime(2/CLOCK_REALTIME): 1395397524.932475314 Equal: 0
Last value from clock_gettime(2/CLOCK_MONOTONIC_FAST): 273152.517350067 Equal: 0
Last value from clock_gettime(2/CLOCK_MONOTONIC): 273152.446504821 Equal: 0
Also check to see what your timecounter settings are:
sysctl kern.timecounter
Regards
Steve
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