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Date: Mon, 24 Nov 2008 17:05:03 -0800 (PST) From: David Rientjes <rientjes@...gle.com> To: Randy Dunlap <randy.dunlap@...cle.com> cc: Andrew Morton <akpm@...ux-foundation.org>, peterz@...radead.org, david@...morbit.com, cl@...ux-foundation.org, linux-kernel@...r.kernel.org Subject: Re: [patch 2/2] mm: add dirty_background_bytes and dirty_bytes sysctls On Mon, 24 Nov 2008, Randy Dunlap wrote: > >> - if (background_ratio >= dirty_ratio) > >> - background_ratio = dirty_ratio / 2; > >> + dirty_ratio = vm_dirty_ratio; > >> + if (dirty_ratio < 5) > >> + dirty_ratio = 5; > >> + dirty = (dirty_ratio * available_memory) / 100; > >> + } > >> + > >> + if (dirty_background_bytes) > >> + background = (dirty_background_bytes + PAGE_SIZE) / PAGE_SIZE; > > > > DIV_ROUND_UP()? > > Note that DIV_ROUND_UP() would make that > > background = (dirty_background_byte + PAGE_SIZE - 1) / PAGE_SIZE; > > but that's usually what is needed/intended. > Good point. If we were to do this, then dirty_bytes and dirty_background_bytes should use 1 instead of 0 as the minimum acceptable value in proc_dointvec_minmax(). Otherwise, get_dirty_limits() would return 0 pages for the dirty limit when 0 is written to either file since integer division truncates and we'd be in a constant state of writeback :) -- 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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