linux-kernel - Re: yield API

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 02 Oct 2007 11:24:18 -0400
From:	Douglas McNaught <doug@...aught.org>
To:	"linux-os \(Dick Johnson\)" <linux-os@...logic.com>
Cc:	"Ingo Molnar" <mingo@...e.hu>,
	"David Schwartz" <davids@...master.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: yield API

"linux-os \(Dick Johnson\)" <linux-os@...logic.com> writes:

> Whether or not there is a POSIX definition of sched_yield(),
> there is a need for something that will give up the CPU
> and not busy-wait. There are many control applications
> where state-machines are kept in user-mode code. The code
> waits for an event. It shouldn't be spinning, wasting
> CPU time, when the kernel can be doing file and network
> I/O with the wasted CPU cycles.

These "control applications" would be real-time processes, for which
(AIUI) sched_yield() behavior is completely well-defined and
implemented as such by Linux.  The question here is how useful the
call is for SCHED_OTHER (non-real-time) processes, for which it has no
well-defined semantics.

-Doug
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/