From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugme-daemon@bugzilla.kernel.org
Subject: [Bug 9729] New: ondemand cpufreq governor doesn't see when
kcryptd/dm-crypt is busy
Date: Fri, 11 Jan 2008 04:29:30 -0800 (PST)
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To: cpufreq@www.linux.org.uk
http://bugzilla.kernel.org/show_bug.cgi?id=9729
Summary: ondemand cpufreq governor doesn't see when kcryptd/dm-
crypt is busy
Product: Power Management
Version: 2.5
KernelVersion: 2.6.23.11
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: cpufreq
AssignedTo: cpufreq@www.linux.org.uk
ReportedBy: tch@wpkg.org
Distribution: Debian Etch
Problem Description:
It seems that ondemand cpufreq governor doesn't see when CPU is busy with
kcryptd/dm-crypt.
With ondemand cpufreq governor reads/writes from a dm-crypt device will be very
slow.
Steps to reproduce
First, let's use "ondemand" governor - reads will be only about ~8 MB/s.
# echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
# cat /proc/cpuinfo | grep MHz
cpu MHz : 349.991
cpu MHz : 349.991
# echo 3 > /proc/sys/vm/drop_caches
# dd if=/dev/san2_data/test of=/dev/null bs=64k count=1000
1000+0 records in
1000+0 records out
65536000 bytes (66 MB) copied, 8.64089 seconds, 7.6 MB/s
Now, let's use performance governor - we get almost 60 MB/s:
# echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
# cat /proc/cpuinfo | grep MHz
cpu MHz : 2799.930
cpu MHz : 2799.930
# echo 3 > /proc/sys/vm/drop_caches
# dd if=/dev/san2_data/test of=/dev/null bs=64k count=1000
1000+0 records in
1000+0 records out
65536000 bytes (66 MB) copied, 1.14821 seconds, 57.1 MB/s
Some system information:
# uname -a
Linux san2 2.6.23.12-pata #10 SMP Fri Dec 21 15:59:53 CET 2007 i686 GNU/Linux
# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Xeon(TM) CPU 2.80GHz
stepping : 9
cpu MHz : 349.991
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe pebs bts sync_rdtsc
cid xtpr
bogomips : 5585.42
clflush size : 64
processor : 1
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Xeon(TM) CPU 2.80GHz
stepping : 9
cpu MHz : 349.991
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe pebs bts sync_rdtsc
cid xtpr
bogomips : 5582.16
clflush size : 64
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