[#3877] echo 0 > /proc/sys/vm/pagecache_ratio may hang shell
Submitted By: Yi Li
Open Date
2008-01-31 21:23:23 Close Date
2008-03-17 18:47:23
Priority:
Very Low Assignee:
Nobody
Status:
Closed Fixed In Release:
N/A
Found In Release:
N/A Release:
svn trunk
Category:
N/A Board:
STAMP
Processor:
BF537 Silicon Revision:
Is this bug repeatable?:
Yes Resolution:
Fixed
Uboot version or rev.:
Toolchain version or rev.:
svn trunk
App binary format:
N/A
Summary: echo 0 > /proc/sys/vm/pagecache_ratio may hang shell
Details:
Just log here - not sure this is expected behavior or bug.
When using jffs2 in NOR flash as rootfs, doing bellow operation will hang the shell.
root:/> mount
rootfs on / type rootfs (rw)
/dev/root on / type jffs2 (rw)
proc on /proc type proc (rw)
ramfs on /var type ramfs (rw)
sysfs on /sys type sysfs (rw)
root:/> echo 50 > /proc/sys/vm/pagecache_ratio
root:/> echo 3 > /proc/sys/vm/drop_caches
root:/> cat /proc/meminfo
MemTotal: 55324 kB
MemFree: 51248 kB
Buffers: 0 kB
Cached: 148 kB
SwapCached: 0 kB
Active: 36 kB
Inactive: 112 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 0 kB
Mapped: 0 kB
Slab: 1180 kB
SReclaimable: 160 kB
SUnreclaim: 1020 kB
PageTables: 0 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 27660 kB
Committed_AS: 0 kB
VmallocTotal: 0 kB
VmallocUsed: 0 kB
VmallocChunk: 0 kB
root:/> echo 0 > /proc/sys/vm/pagecache_ratio
root:/> echo 3 > /proc/sys/vm/drop_caches
root:/> cat /proc/meminfo
[shell hangs here, it is responsive, but this command never returns]
("echo 1 > /proc/sys/vm/pagecache_ratio" works well)
Follow-ups
--- Sonic Zhang 2008-02-01 01:01:05
The min value should be 10%. How about limit the acceptable value in the driver?
--- Yi Li 2008-02-01 04:07:08
where can I find the 10% limit? I am thinking 0% would disable page cache at
all.
--- Sonic Zhang 2008-02-01 04:15:33
Linux is based on page cache. It can not be disabled completely.
--- Sonic Zhang 2008-02-29 01:20:16
Fixed. Now 10 is the min value.
--- Mike Frysinger 2008-03-17 18:47:23
pagecache no longer in the kernel
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