Messages in this thread | | | Date | Sun, 12 Jan 2014 18:46:07 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC] speeding up the stat() family of system calls... |
| |
* H. Peter Anvin <hpa@zytor.com> wrote:
> On 12/26/2013 10:09 PM, H. Peter Anvin wrote: > > On 12/26/2013 11:00 AM, Linus Torvalds wrote: > >> > >> Interestingly, looking at the cp_new_stat() profiles, the games we > >> play to get efficient range checking seem to actually hurt us. Maybe > >> it's the "sbb" that is just expensive, or maybe it's turning a (very > >> predictable) conditional branch into a data dependency chain instead. > >> Or maybe it's just random noise in my profiles that happened to make > >> those sbb's look bad. > >> > > > > Much to my surprise, this patch adds almost 10K of text to an > > "allyesconfig" build. I wouldn't have expected it. I'll look at > > it some more tomorrow. > > Mystery solved... it is all code added by gcov &c because a new > (inline) function is added to the code base. So it is fluff, not > real.
Yeah, defconfig builds are better for size comparisons, at least on x86 they are distro-config derived so a lot more relevant to real life than allyesconfig or allmodconfig.
Thanks,
Ingo
| |