[ltt-dev] Degression from "fix-x86_64-sysenter-trace-race"

[Zhaolei]

* Mathieu Desnoyers Wrote:
> * Zhaolei (zhaolei at cn.fujitsu.com) wrote:
>> Hello,
>>
>> I tested lttng's performance by tbench program in x86_64 platform.
>> And I found patch named "fix-x86_64-sysenter-trace-race" makes large
>> degression(about 5%).
>> Here is test result:
>>
>> [----------PATCH----------]                     [TBENCH]
>> lttng-kernel-trace-thread-flag-s390		1317.08
>> lttng-kernel-trace-thread-flag-sh		1315.61
>> lttng-kernel-trace-thread-flag-sparc		1305.02
>> lttng-kernel-trace-thread-flag-sparc64		1314.06
>> lttng-kernel-trace-thread-flag-um		1316.35
>> fix-x86_64-sysenter-trace-race			1250.89
>> lttng-kernel-trace-thread-flag-x86		1259.07
>> lttng-kernel-trace-thread-flag-xtensa		1252.86
>> lttng-kernel-trace-thread-flag-api		1253.35
>> lttng-use-kernel-trace-thread-flag-api		1251.9
>> stringify-support-commas			1247.11
>>
>> And if I remove this patch, degression is not happened:
>> [----------PATCH----------]                     [TBENCH]
>> lttng-kernel-trace-thread-flag-s390		1307.73
>> lttng-kernel-trace-thread-flag-sh		1317.33
>> lttng-kernel-trace-thread-flag-sparc		1306.85
>> lttng-kernel-trace-thread-flag-sparc64		1303.62
>> lttng-kernel-trace-thread-flag-um		1312.08
>> lttng-kernel-trace-thread-flag-x86		1308.5
>> lttng-kernel-trace-thread-flag-xtensa		1310.77
>> lttng-kernel-trace-thread-flag-api		1309.05
>> lttng-use-kernel-trace-thread-flag-api		1310.26
>> stringify-support-commas			1307.69
>>
>> I want to know system's benchmark when lttng turn off,
>> so test environment is following:
>> - Compile kernel with lttng patch up to given one and default config,
>> - Install kernel, Reboot system,
>>   (don't load any lttng module, don't run ltt-arm or lttctl)
>> - Begin tbench test.
>>
>> Plarform is RHEL5.2 root filesystem with linux-2.6.27.7 and lttng-0.60 patchs.
>> Hardware is 4 * Intel(R) Xeon(R) X5260 at 3.33GHz with 4G memory.
>>
>> I think [fix-x86_64-sysenter-trace-race] should not leads so large degression,
>> But I tested several times and result is near.
>>
> 
> Hrm, interesting. Can you give your full kernel .config ? I'd like to
> see if the _TIF_SYSCALL_AUDIT or _TIF_SECCOMP bits are set.
Hello, Mathieu

kernel config is send as attachment.
I use RHEL's default config with ltt support.

B.R.
Zhaolei

> 
> If you have a better way to support asynchronously changing the thread
> flags and still have the affected running threads running correctly, I'm
> willing to consider it.
> 
> Mathieu
> 
>> B.R.
>> Zhaolei
>>
>>
>> _______________________________________________
>> ltt-dev mailing list
>> ltt-dev at lists.casi.polymtl.ca
>> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
>>
> 

-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: config.ltt
URL: <http://lists.casi.polymtl.ca/pipermail/lttng-dev/attachments/20090113/73f371c8/attachment-0001.txt>