On Mon, 2012-07-09 at 15:24 -0400, Jeff Mahoney wrote:
On 7/9/12 3:07 PM, Jean Delvare wrote:
Le lundi 09 juillet 2012 à 10:44 -0400, Jeff Mahoney a écrit :
On 7/9/12 10:37 AM, Jean Delvare wrote:
So, unless someone objects by then, I'll set CONFIG_CC_STACKPROTECTOR=y in i386 and x86_64 kernels tomorrow.
Thanks for looking into this, Jean. Since we don't have a bnc in the commit log to see what the performance degradation looked like originally, I'd like to see some analysis now to actually confirm whether it makes a difference anymore.
openSUSE 12.2 was supposed to be released in two days time but was delayed due to too much churn (among other things). If there is a performance difference, I'd prefer to know about it before we do the change rather than depend on post-release bug reports and the accompanying hand-wringing over whether to revert it.
Are you simply suggesting that I should change the configuration for master only and not the openSUSE-12.2 branch? Or should I wait even for master?
I admit I'm not sure how to test for performance regression. With CONFIG_CC_STACKPROTECTOR_ALL it was relatively obvious, but now that only selected functions get the protection, I can imagine that the performance hit completely depends on the drivers, filesystem etc. in use.
A quick look makes it seem like it really only has an effect during context switch.
Mike - What would you use to test this?
A pinned fork()/sched_yield() pair for pure context switch. -Mike -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org