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Message-ID: <9f924d250905220239k1dc36aaeib3c2ec955267038a@mail.gmail.com> Date: Fri, 22 May 2009 11:39:31 +0200 From: Ad van den Broek <advandenbroek.nl@...il.com> To: linux-kernel@...r.kernel.org Subject: PIPE_SIZE aspects I searched the net regarding PIPE_SIZE aspects. This is what I found: * The constant PIPE_SIZE establishes the number of bytes allocated for a pipe (the size of the pipe buffer) * The default of PIPE_SIZE (in Linux 2.4) is PAGE_SIZE. * The default of PIPE_SIZE (in Linux 2.6) is 64K. * PAGE_SIZE (in Linux 2.4) is CPU/hw depending, may not be changed and is 4K for x86. * PAGE_SIZE (in Linux 2.6) is 64K. * PIPE_SIZE can be changed in Linux 2.4, but it should be NOT larger than PAGE_SIZE or a patch should be implemented I found a patch (I believe the author is Julian Bradfield) at http://lse.sourceforge.net/pipe/2.4.9-pipe.patch and this patch is modified by Manfred Spraul which version can be found at http://linuxperf.sourceforge.net/patches/2.4.13-largepipe.patch It is tested with PIPE_SIZE from 1 upto 2,4,8 pages. and the result is at http://lse.sourceforge.net/pipe/pipe-report.txt My questions: Is the above info correct ? Is the large pipe patch still correct for last 2.4.x versions ? Is such a patch also required/possible in Linux 2.6 to allow PIPE_SIZE > PAGE_SIZE or is that different in 2.6 ? -- With best regards, Ad van den Broek The Netherlands -- 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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