Hi All,
A wee problem with a kernel panic: kmem_map too small. The panic occurs on a largish network file copies (>8G) from a Windows 7 box to FreeBSD 8.0-RELEASE-p3 running ZFS v13. Interestingly, no such panic occurred when the system was running FreeBSD 7.2.
The panic occurs regardless of whether the file copy is done by samba or, say, scp. ZFS prefetch is turned off by default, and sysctl confirms that it is, in fact, turned off.
Now, the system is running on an Intel Atom 230 with 2G of RAM, so my reading suggests that something has changed in 8.0 and now some tuning is necessary. However, all my attempts at tuning are not making the problem go away.
Here are my variables from loader.conf, tuned according to readings on a variety of sites, including this one.
This particular config creates a panic at 533815796 bytes. As a general rule, the panic always seems to occur at about the threshold of zfs.arc_max. The problem over successive panics (sorry but I don't have a written record) seems to be that ZFS runs across its defined arc_max threshold.
I have tried a variety of settings for these variables to no effect. Advice across the web is scattered and contradictory. I have tried a variety of settings for zfs.arc_max and zfs.arc_min to no avail. Some people (not of this site) have suggested (counter-intuitively) to set kmem_size_max to 1.5x physical memory. I did try that to no effect. Others have suggested (intuitively), that kmem_size_max should not be greater than the total system memory is a better option. But, even then there is a panic.
Any suggestions? Thanks for any help you can offer because I am running out of ideas.
Best,
Jay.
A wee problem with a kernel panic: kmem_map too small. The panic occurs on a largish network file copies (>8G) from a Windows 7 box to FreeBSD 8.0-RELEASE-p3 running ZFS v13. Interestingly, no such panic occurred when the system was running FreeBSD 7.2.
The panic occurs regardless of whether the file copy is done by samba or, say, scp. ZFS prefetch is turned off by default, and sysctl confirms that it is, in fact, turned off.
Now, the system is running on an Intel Atom 230 with 2G of RAM, so my reading suggests that something has changed in 8.0 and now some tuning is necessary. However, all my attempts at tuning are not making the problem go away.
Here are my variables from loader.conf, tuned according to readings on a variety of sites, including this one.
Code:
vfs.zfs.arc_min="128M"
vfs.zfs.arc_max="512M"
vm.kmem_size="768M"
vm.kmem_size_max="1024M"
This particular config creates a panic at 533815796 bytes. As a general rule, the panic always seems to occur at about the threshold of zfs.arc_max. The problem over successive panics (sorry but I don't have a written record) seems to be that ZFS runs across its defined arc_max threshold.
I have tried a variety of settings for these variables to no effect. Advice across the web is scattered and contradictory. I have tried a variety of settings for zfs.arc_max and zfs.arc_min to no avail. Some people (not of this site) have suggested (counter-intuitively) to set kmem_size_max to 1.5x physical memory. I did try that to no effect. Others have suggested (intuitively), that kmem_size_max should not be greater than the total system memory is a better option. But, even then there is a panic.
Any suggestions? Thanks for any help you can offer because I am running out of ideas.
Best,
Jay.