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Date: Sun, 30 Sep 2012 11:38:45 +0200 From: Pierre Beck <mail@...rre-beck.de> To: linux-kernel@...r.kernel.org Subject: 3.6-rc7 32-bit PAE miscalculates dirty page limits Hi, there seems to be a bug in either ext4 or VM code triggered with 16 GB memory when compiled with 32-bit and PAE. dirty_background_ratio defaults to 10, dirty_ratio to 20. But in effect, dirty pages are strongly limited (zero or negative?). I observed extreme I/O wait states and slow disk access. A quick cure was to set dirty_bytes and dirty_background_bytes to sane values, overriding the ratios. An educated guess: the result of dirty_ratio calculation is stored as an unsigned 32-bit integer and overflows? Greetings, Pierre Beck -- 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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