linux-kernel - Re: Network slowdown due to CFS

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, 2 Oct 2007 08:08:48 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	David Schwartz <davids@...master.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Network slowdown due to CFS


* David Schwartz <davids@...master.com> wrote:

> > (user-space spinlocks are broken beyond words for anything but 
> > perhaps SCHED_FIFO tasks.)
> 
> User-space spinlocks are broken so spinlocks can only be implemented 
> in kernel-space? Even if you use the kernel to schedule/unschedule the 
> tasks, you still have to spin in user-space.

user-space spinlocks (in anything but SCHED_FIFO tasks) are pretty 
broken because they waste CPU time. (not as broken as yield, because 
"wasting CPU time" is a more deterministic act, but still broken) Could 
you cite a single example where user-space spinlocks are technically the 
best solution?

	Ingo
-
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/