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Message-ID: <20071002060848.GB18588@elte.hu> 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/
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