Filesystem bug? "sync" hangs...

Filesystem bug? "sync" hangs...

[Jeff Garzik]

Kernel 2.4.7-pre3 on alpha.

The initial phase of an RPM build is unpacking a tarball and applying
patches, which is a bunch of writes followed by a update of read/write
updates.  A lot of write activity, basically.  RPM build is running at
normal priority as a normal user.

In another xterm, su'd in a shell that is renice'd to -14, I run "sync"
during all this write activity.  It hangs for 17 seconds before I get
impatient, stop counting, and suspend the RPM build process.  sync
continues to block, not returning to the command prompt.  I run dmesg
(generated read activity?), and sync finally returns.

The RPM build process continues unpacking/writing files without
appearing to slow in window 1 while sync blocks in window 2.

I have not seen this behavior before, but I do not recall trying 'sync'
specifically during heavy write activity before.  This behavior is
reproducible.

-- 
Jeff Garzik      | A recent study has shown that too much soup
Building 1024    | can cause malaise in laboratory mice.
MandrakeSoft     |