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Re: [PATCH gnumach 1/3] kern: improve assert
From: |
Justus Winter |
Subject: |
Re: [PATCH gnumach 1/3] kern: improve assert |
Date: |
Fri, 19 Dec 2014 11:19:34 +0100 |
User-agent: |
alot/0.3.5 |
Quoting Samuel Thibault (2014-12-19 02:54:17)
> Justus Winter, le Fri 19 Dec 2014 02:48:56 +0100, a écrit :
> > Use the ternary operator to implement `assert' like it is done in the
> > glibc. The glibcs changelog does not mention the rationale behind
> > this change, but it does improve our IPC performance.
>
> Mmm, is it not a matter of changing the estimation of probability of
> branching from the compiler? I guess using an "unlikely" macro would
> get the same benefit in a much more readable and compiler-portable way?
Yes, I tried that first, without getting any improvements. The libc
once used __builtin_expect for assert too, but stopped (they didn't
mention why in the changelog).
Lacking a specialized IPC microbenchmark I'm using iperf to measure
TCP performance (over netdde), which is greatly influenced by IPC
performance.
I'll work a little on my IPC microbenchmark, and try to reproduce my
findings with it.
Justus
Re: [PATCH gnumach 1/3] kern: improve assert, Samuel Thibault, 2014/12/20