Joerg Schilling wrote:
Phil Harman <phil.har...@sun.com> wrote:
ZFS doesn't mix well with mmap(2). This is because ZFS uses the ARC
instead of the Solaris page cache. But mmap() uses the latter. So if
anyone maps a file, ZFS has to keep the two caches in sync.
cp(1) uses mmap(2). When you use cp(1) it brings pages of the files it
copies into the Solaris page cache. As long as they remain there ZFS
will be slow for those files, even if you subsequently use read(2) to
access them.
If you reboot, your cpio(1) tests will probably go fast again, until
Do you believe that reboot is the only way to reset this?
No, but from my iPod I didn't have the patience to write a fuller
explanation :)
See ...
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/fs/zfs/zfs_vnops.c#514
We take the long path is the vnode has any pages cached in the page cache.
So instead of a reboot, you should also be able to export/import the
pool or unmount/mount the filesystem.
Also, if you didn't touch the file for a long time, and had lots of
other page cache churn, the file might eventually get expunged from the
page cache.
Phil
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