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Stop maximizing the bitmap buffer to reduce the risk of OOM.

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This is a backport of the following upstream commit.

commit 0b732828091a545185ad13d0b2e6800600788d61
Author: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Date:   Tue Jun 10 13:57:29 2014 +0900

    [PATCH 3/3] Stop maximizing the bitmap buffer to reduce the risk of OOM.

    We tried to maximize the bitmap buffer to get the best performance,
    but the performance degradation caused by multi-cycle processing
    looks very small according to the benchmark on 2TB memory:

      https://lkml.org/lkml/2013/3/26/914

    This result means we don't need to make an effort to maximize the
    bitmap buffer, it will just increase the risk of OOM.

    This patch sets a small fixed value (4MB) as a safety limit,
    it may be safer and enough in most cases.

    Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>

Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This commit is contained in:
Baoquan He 2014-07-15 15:50:25 +08:00 committed by WANG Chao
parent 23d1c25fd5
commit e5769870b1
2 changed files with 75 additions and 0 deletions
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73
kexec-tools-2.0.4-makedumpfile-Stop-maximizing-the-bitmap-buffer-to-reduc.patch Normal file
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@ -0,0 +1,73 @@
From 0b732828091a545185ad13d0b2e6800600788d61 Mon Sep 17 00:00:00 2001
From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Date: Tue, 10 Jun 2014 13:57:29 +0900
Subject: [PATCH] [PATCH 3/3] Stop maximizing the bitmap buffer to reduce the
risk of OOM.
We tried to maximize the bitmap buffer to get the best performance,
but the performance degradation caused by multi-cycle processing
looks very small according to the benchmark on 2TB memory:
https://lkml.org/lkml/2013/3/26/914
This result means we don't need to make an effort to maximize the
bitmap buffer, it will just increase the risk of OOM.
This patch sets a small fixed value (4MB) as a safety limit,
it may be safer and enough in most cases.
Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Signed-off-by: Baoquan He <bhe@redhat.com>
---
makedumpfile.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/makedumpfile.c b/makedumpfile.c
index b8f1ec4..3884aa5 100644
--- a/makedumpfile-1.5.6/makedumpfile.c
+++ b/makedumpfile-1.5.6/makedumpfile.c
@@ -8946,13 +8946,15 @@ out:
/*
- * Choose the lesser value of the two below as the size of cyclic buffer.
- * - the size enough for storing the 1st/2nd bitmap for the whole of vmcore
- * - 80% of free memory (as safety limit)
+ * Choose the less value of the three below as the size of cyclic buffer.
+ * - the size enough for storing the 1st or 2nd bitmap for the whole of vmcore
+ * - 4MB as sufficient value
+ * - 60% of free memory as safety limit
*/
int
calculate_cyclic_buffer_size(void) {
unsigned long long limit_size, bitmap_size;
+ const unsigned long long maximum_size = 4 * 1024 * 1024;
if (info->max_mapnr <= 0) {
ERRMSG("Invalid max_mapnr(%llu).\n", info->max_mapnr);
@@ -8960,17 +8962,18 @@ calculate_cyclic_buffer_size(void) {
}
/*
- * We should keep the size of cyclic buffer within 80% of free memory
- * for safety.
+ * At least, we should keep the size of cyclic buffer within 60% of
+ * free memory for safety.
*/
- limit_size = get_free_memory_size() * 0.8;
+ limit_size = get_free_memory_size() * 0.6;
bitmap_size = info->max_mapnr / BITPERBYTE;
/* if --split was specified cyclic buffer allocated per dump file */
if (info->num_dumpfile > 1)
bitmap_size /= info->num_dumpfile;
- info->bufsize_cyclic = MIN(limit_size, bitmap_size);
+ /* 4MB will be enough for performance according to benchmarks. */
+ info->bufsize_cyclic = MIN(MIN(limit_size, maximum_size), bitmap_size);
return TRUE;
}
--
1.8.5.3

2
kexec-tools.spec
View File

@ -80,6 +80,7 @@ Patch603: kexec-tools-2.0.4-makedumpfile-Introduce-the-mdf_pfn_t-type.patch
Patch604: kexec-tools-2.0.4-makedumpfile-Fix-free-bitmap_buffer_cyclic-error.patch
Patch605: kexec-tools-2.0.4-makedumpfile-Remove-the-1st-bitmap-buffer-from-the-ELF-.patch
Patch606: kexec-tools-2.0.4-makedumpfile-Move-counting-pfn_memhole-for-cyclic-mode.patch
Patch607: kexec-tools-2.0.4-makedumpfile-Stop-maximizing-the-bitmap-buffer-to-reduc.patch
%description
kexec-tools provides /sbin/kexec binary that facilitates a new
@ -121,6 +122,7 @@ tar -z -x -v -f %{SOURCE23}
%patch604 -p1
%patch605 -p1
%patch606 -p1
%patch607 -p1
tar -z -x -v -f %{SOURCE13}