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Date: Tue, 13 Jul 2004 03:08:15 -0700
From: William Lee Irwin III <wli@holomorphy.com>
To: Andrew Morton <akpm@osdl.org>
Cc: Con Kolivas <kernel@kolivas.org>, devenyga@mcmaster.ca, ck@vds.kolivas.org,
       linux-kernel@vger.kernel.org
Subject: Re: Preempt Threshold Measurements
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On Mon, Jul 12, 2004 at 09:01:07PM -0700, Andrew Morton wrote:
> This is a false positive.  Nothing is setting need_resched(), so
> unmap_vmas() doesn't bother dropping the lock.

I guess I sent too many updates and the whole thing got dropped. The false
positives were fixed in this way:

--- timing-2.6.7.orig/mm/memory.c	2004-06-15 22:19:22.000000000 -0700
+++ timing-2.6.7/mm/memory.c	2004-07-12 05:33:17.000000000 -0700
@@ -558,14 +558,17 @@
 			zap_bytes -= block;
 			if ((long)zap_bytes > 0)
 				continue;
-			if (!atomic && need_resched()) {
+			zap_bytes = ZAP_BLOCK_SIZE;
+			if (!atomic)
+				continue;
+			touch_preempt_timing();
+			if (need_resched()) {
 				int fullmm = tlb_is_full_mm(*tlbp);
 				tlb_finish_mmu(*tlbp, tlb_start, start);
 				cond_resched_lock(&mm->page_table_lock);
 				*tlbp = tlb_gather_mmu(mm, fullmm);
 				tlb_start_valid = 0;
 			}
-			zap_bytes = ZAP_BLOCK_SIZE;
 		}
 	}
 	return ret;