From: Ricardo Nabinger Sanchez <rnsanchez@terra.com.br>
To: linux-kernel@vger.kernel.org
Cc: Frank.Cornelis@elis.ugent.be
Subject: Re: [PATCH] sched: CPU_THRESHOLD
Date: Sat, 23 Aug 2003 19:57:40 -0300 [thread overview]
Message-ID: <20030823195740.7133874d.rnsanchez@terra.com.br> (raw)
hello Frank,
> - *imbalance = (max_load - nr_running) / 2;
> + *imbalance = (max_load - nr_running) >> 1;
I think it is a good coding practice to keep things human-readable.
In this code snippet, the division by 2 is quickly understood by most
readers (specially those who didn't write it). The right shift may
obfuscate the real meaning of this operation, which is a single
division by 2, not a bit-oriented expression.
Assuming that sched.c will be compiled with optimizations enabled, the
compiler will change the human-readable division by a fast machine
right shift operation, whenever possible (gcc surely will).
Thus, we keep the kernel code more readable, and sometimes let the
compiler apply newer (and hopefully faster) optimizations than some
tricks we have known as fastest available.
Regards, and please let me know what do you think about it.
--
Ricardo Nabinger Sanchez
GNU/Linux #140696 [http://counter.li.org]
Slackware Linux
next reply other threads:[~2003-08-23 22:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-23 22:57 Ricardo Nabinger Sanchez [this message]
2003-08-25 17:12 ` [PATCH] sched: CPU_THRESHOLD Timothy Miller
-- strict thread matches above, loose matches on Subject: below --
2003-08-22 12:43 Frank Cornelis
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