Subject: Re: gettimeofday scalability

From: [email-masked]
Date: Tue, 05 Oct 2004 20:16:33 +0100

Andrea Arcangeli wrote:
> On Tue, Oct 05, 2004 at 05:36:06PM +0100, [email-masked] wrote:
> 
>>So can anyone summarise the relative merits of these locking
>>mechanisms, before I start benchmarking?
> 
> 
> frlock/seqlock (2.4/2.6 respectively) is the way to go, no write
> starvation, and zero cacheline bouncing. 

Cheers.

Perhaps the confusing comment wrt brlock at the
top of seqlock.h can be changed so?

> upgrade to x86-64, there I implemented gettimeofday with vsyscalls which
> also avoids entering exiting userspace which becomes the by far biggest
> overhead after using seqlock. (speedup is tenfold or so)

This is all in kernel space.
However Stephen's suggestion of reading the tsc in user space
may be a runner, as I just care about relative times.

thanks guys!

Pádraig.