On Fri, 2014-07-25 at 12:45 -0700, Sergey Oboguev wrote: > [This is a repost of the message from few day ago, with patch file > inline instead of being pointed by the URL.] > > This patch is intended to improve the support for fine-grain parallel > applications that may sometimes need to change the priority of their threads > at > a very high rate, hundreds or even thousands of times per scheduling > timeslice. > > These are typically applications that have to execute short or very short > lock-holding critical or otherwise time-urgent sections of code at a very high > frequency and need to protect these sections with "set priority" system calls, > one "set priority" call to elevate current thread priority before entering the > critical or time-urgent section, followed by another call to downgrade thread > priority at the completion of the section. Due to the high frequency of > entering and leaving critical or time-urgent sections, the cost of these "set > priority" system calls may raise to a noticeable part of an application's > overall expended CPU time. Proposed "deferred set priority" facility allows to > largely eliminate the cost of these system calls.
So you essentially want to ship preempt_disable() off to userspace? (smiles wickedly, adds CCs) -Mike > Instead of executing a system call to elevate its thread priority, an > application simply writes its desired priority level to a designated memory > location in the userspace. When the kernel attempts to preempt the thread... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
