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
| ||
|
Date: Sat, 28 Apr 2007 23:53:45 +0200 From: matthieu castet <castet.matthieu@...e.fr> To: Linux Kernel list <linux-kernel@...r.kernel.org> Subject: High Resolution Timer DOS Hi, some programs need to do some short of busyloop. It was often implemented as : while (1) { if (can_do_stuff) { do_stuff(); } else //sleep a very short of time usleep(1); } usleep(1) or equivalent where used instead of sched_yield, because of some priority issue. IIRC doing sched_yield, make the process appears like an interactive process, so it has better priority and get call more often. But now if high res timer are enabled, these programs while cause something like a DOS : the context switch per second will be bigger than 500 000 and the cpu usage will be very high. I don't know if such problem are already know, but I believe a warning about such issues should be in the Kconfig description. Matthieu - 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/
Powered by blists - more mailing lists