On 29/11/2007, at 6:49 PM, Martin wrote:
> Please excluse that my comment is cross-posted to both the Xen and > zfs discuss forums, I didn't notice it on the Xen forum until I had > posted. Anyway, here goes. Any info, testing, etc please contact me. > > > Regarding the following that I also hit, see > http://www.opensolaris.org/jive/thread.jspa?messageID=180995 > and if any further details or tests are required, I would be happy > to assist. > >> 3/ Problem with DMA under Xen ... e.g. my areca raid cards works >> perfect on a 8GB box without xen but because of the way xen allocates >> memory... I am forced to allocate only 1 or 2 gig for the dom0 or the >> areca drivers will fail miserably trying to do DMA above the first 4G >> address space. This very same problem affected xen under linux over a >> year ago and seems to have been addressed. Several persons on the ZFS >> discuss list who complain about poor ZFS IO performance are affected >> by this issue. > > This should be relatively easy to fix assuming I can get > access to similar H/W. > > Do you get any error messages? We do have a bug in contig alloc > (allocs too much memory) which was recently found which is > affecting nv_sata based systems. It may be related to that > or something that the driver could be doing better. > > Can you send me more details around your setup (card your > using, what's connected to it, where you got the driver > and what version you have), behavior and perf on metal, > behavior and perf on xVM. The workaround is to limit the dom0 memory to 1024M, reserving 7 gig for my domU's. kernel$ /boot/$ISADIR/xen.gz dom0_mem=1024M com1=57600,8n1 console=com1 Here are the relevant threads. I posted with the logs and errors in some of them: http://www.opensolaris.org/jive/thread.jspa?messageID=162481𧪱 http://www.opensolaris.org/jive/thread.jspa?messageID=162462𧪞 http://www.opensolaris.org/jive/thread.jspa?messageID=162459𧪛 and recently Martints had the same problem: http://www.opensolaris.org/jive/thread.jspa?threadID=43518&start=0&tstart=0 _______________________________________________ xen-discuss mailing list [email protected]
