74 lines
2.5 KiB
Diff
74 lines
2.5 KiB
Diff
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From 0b732828091a545185ad13d0b2e6800600788d61 Mon Sep 17 00:00:00 2001
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From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
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Date: Tue, 10 Jun 2014 13:57:29 +0900
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Subject: [PATCH] [PATCH 3/3] Stop maximizing the bitmap buffer to reduce the
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risk of OOM.
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We tried to maximize the bitmap buffer to get the best performance,
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but the performance degradation caused by multi-cycle processing
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looks very small according to the benchmark on 2TB memory:
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https://lkml.org/lkml/2013/3/26/914
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This result means we don't need to make an effort to maximize the
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bitmap buffer, it will just increase the risk of OOM.
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This patch sets a small fixed value (4MB) as a safety limit,
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it may be safer and enough in most cases.
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Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
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Signed-off-by: Baoquan He <bhe@redhat.com>
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---
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makedumpfile.c | 17 ++++++++++-------
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1 file changed, 10 insertions(+), 7 deletions(-)
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diff --git a/makedumpfile.c b/makedumpfile.c
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index b8f1ec4..3884aa5 100644
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--- a/makedumpfile-1.5.6/makedumpfile.c
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+++ b/makedumpfile-1.5.6/makedumpfile.c
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@@ -8946,13 +8946,15 @@ out:
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/*
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- * Choose the lesser value of the two below as the size of cyclic buffer.
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- * - the size enough for storing the 1st/2nd bitmap for the whole of vmcore
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- * - 80% of free memory (as safety limit)
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+ * Choose the less value of the three below as the size of cyclic buffer.
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+ * - the size enough for storing the 1st or 2nd bitmap for the whole of vmcore
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+ * - 4MB as sufficient value
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+ * - 60% of free memory as safety limit
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*/
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int
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calculate_cyclic_buffer_size(void) {
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unsigned long long limit_size, bitmap_size;
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+ const unsigned long long maximum_size = 4 * 1024 * 1024;
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if (info->max_mapnr <= 0) {
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ERRMSG("Invalid max_mapnr(%llu).\n", info->max_mapnr);
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@@ -8960,17 +8962,18 @@ calculate_cyclic_buffer_size(void) {
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}
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/*
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- * We should keep the size of cyclic buffer within 80% of free memory
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- * for safety.
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+ * At least, we should keep the size of cyclic buffer within 60% of
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+ * free memory for safety.
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*/
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- limit_size = get_free_memory_size() * 0.8;
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+ limit_size = get_free_memory_size() * 0.6;
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bitmap_size = info->max_mapnr / BITPERBYTE;
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/* if --split was specified cyclic buffer allocated per dump file */
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if (info->num_dumpfile > 1)
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bitmap_size /= info->num_dumpfile;
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- info->bufsize_cyclic = MIN(limit_size, bitmap_size);
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+ /* 4MB will be enough for performance according to benchmarks. */
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+ info->bufsize_cyclic = MIN(MIN(limit_size, maximum_size), bitmap_size);
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return TRUE;
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}
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--
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1.8.5.3
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