39 lines
1.4 KiB
Diff
39 lines
1.4 KiB
Diff
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From 5707bfdf0aac985e8e82c9a5004eb458d1d79801 Mon Sep 17 00:00:00 2001
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From: =?utf-8?q?Dan=20Hor=C3=A1k?= <dan@danny.cz>
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Date: Fri, 30 Oct 2009 11:23:08 +0100
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Subject: [PATCH] update readahead value for better performance
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Description: dasd,zfcp: Add udev rule to set increased "default max readahead"
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Symptom: Sequential read performance on disks is not as good as it could be.
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Problem: The current "default max readahead" defined by the kernel is too
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small for s390 (128 kb).
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Solution: Add udev rule to set a better default value (512 kb). This will
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increase sequential read performance up to 40%.
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---
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etc/udev/rules.d/60-readahead.rules | 13 +++++++++++++
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1 files changed, 13 insertions(+), 0 deletions(-)
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create mode 100644 etc/udev/rules.d/60-readahead.rules
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diff --git a/etc/udev/rules.d/60-readahead.rules b/etc/udev/rules.d/60-readahead.rules
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new file mode 100644
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index 0000000..3133c66
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--- /dev/null
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+++ b/etc/udev/rules.d/60-readahead.rules
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@@ -0,0 +1,13 @@
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+#
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+# Rules to set an increased default max readahead size for s390 disk devices
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+# This file should be installed in /etc/udev/rules.d
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+#
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+
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+SUBSYSTEM!="block", GOTO="ra_end"
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+
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+ACTION!="add", GOTO="ra_end"
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+# on device add set initial readahead to 512 (instead of in kernel 128)
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+KERNEL=="sd*[!0-9]", ATTR{queue/read_ahead_kb}="512"
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+KERNEL=="dasd*[!0-9]", ATTR{queue/read_ahead_kb}="512"
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+
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+LABEL="ra_end"
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--
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1.6.3.3
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