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Message-ID: <a57051ba1001110229q2ca28ffbqea37d07735debb52@mail.gmail.com> Date: Mon, 11 Jan 2010 11:29:14 +0100 From: Erik Rigtorp <erik@...torp.com> To: linux-kernel@...r.kernel.org Subject: Monitoring file descriptors without switching context Hi! I'm working on a low latency soft real time system. We currently run on Solaris because it has a lower latency TCP stack and less IPC overhead. I did some experiments with IPC using pipes on Linux. If i use non-blocking pipes and do a busy reading loop I can achieve latencies around 1µs. Using blocking pipes or select()/poll() latencies increase to about 10µs. In general when I use some blocking system call latencies increase because my process will be put on a wait queue and the scheduler will do a context switch. However I have more cores than I have processes/threads so I don't mind blocking a whole core to wait for IO, that way I don't incur a full context switch when the process waits for IO. What I really need is some way to have the hardware block and monitor IO for me. Would it be feasible to implement a special low latency poll() syscall that uses MONITOR/MWAIT instructions to monitor file descriptors? I think in order to utilize new multicore CPUs like the Tileras we need a better signaling mechanism with lower latency than what we currently have using the scheduler. Erik Rigtorp -- 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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