On 10/15/13 2:32 AM, Matthew Ahrens wrote: > On Mon, Oct 14, 2013 at 5:45 PM, Saso Kiselkov <[email protected] > <mailto:[email protected]>> wrote: > > In that > the case, however, I have to ask why the original author put the retry > mechanism in with the pressure valve (halving the memory request size > each iteration) in the first place... > > > I think I wrote that code a decade ago... The idea was probably that > there might not be enough physical memory free -- nothing about > fragmentation. This was back when you could boot off of UFS and then > load the zfs kernel module later (frequently used while debugging). But > I'm not sure that the retry was ever exercised. I can't imagine it has > been used in the past 5 years since (AFAIK) solaris & illumos distros > only boot from ZFS.
Actually there are plenty of distros which boot from UFS (SmartOS being one famous example), but since ZFS is pretty much the only high-data volume capable filesystem on Illumos, I doubt anybody will avoid loading ZFS at some early point in boot. Perhaps if you're running compute-only and might occasionally load ZFS after that, but that's really stretching my imagination. > Linux (and FreeBSD?) may be a different matter. Since the zfs kernel > module can be loaded much after boot, there may be insufficient memory. > Don't know how likely that is, though. Nor do I know how memory > fragmentation (virtual or physical) might come into play on those platforms. Then I guess we should reach out to these guys. FreeBSD & Linux folks: comments please? (Or should we post elsewhere if there are too few people subscribed to this list yet?) Cheers, -- Saso _______________________________________________ developer mailing list [email protected] http://lists.open-zfs.org/mailman/listinfo/developer
