Hello all I am evaluating File I/O performance using Xen & comparing it with baseline (Fedora Core 3, with 2.6.9 kernel). Here are the commands that I use for I/O write I/O: dd if=/dev/zero of=file1 bs=4K count=256K read I/O: dd of=/dev/null if=file1 bs=4K count=256K Here are some numbers (all test results are reported in MB/second) Read I/O - Baseline Fedora Core 3 - 32 - XEN domain 0 - 9.3 - XEN domain 1 - 2.3 Write I/O - Baseline Fedora Core 3 - 22 - XEN domain 0 - 9.8 - XEN domain 1 - 2.5 - Dom0 (without starting xend) results in 2x slower performance - DomU results in 9-10x slower performance I get similar results for domain-1 using both File-based & LVM-based VBD Can someone why I am getting such huge difference in performance compared to baseline ?? Thanks Nauzad ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
> I am evaluating File I/O performance using Xen & comparing it with > baseline (Fedora Core 3, with 2.6.9 kernel). >[snip poor I/O results]> > Can someone why I am getting such huge difference in performance > compared to baseline ??What version of Xen are you using? 2.0.x [preferably 2.0.3]? Did you move /lib/tls out of the way on the various root filesystems? I ask since it should be almost *impossible* to get anything more than a very small % slowdown on disk I/O unless things are very broken -- most of our benchmarks to date show 0% slowdown (and in some cases involving domU, a speedup due to additional buffering). Can you post the output of Xen / dom0 / domU booting, and your configuration files? cheers, S. ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Check that the domain 0 kernel you are using has the appropriate drivers for your hardware. It''s probably using PIO or something daft.> I ask since it should be almost *impossible* to get anything more > than a very small % slowdown on disk I/O unless things are very > broken -- most of our benchmarks to date show 0% slowdown (and > in some cases involving domU, a speedup due to additional buffering).Ian ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Ian Pratt said:>> I ask since it should be almost *impossible* to get anything more >> than a very small % slowdown on disk I/O unless things are very >> broken -- most of our benchmarks to date show 0% slowdown (and >> in some cases involving domU, a speedup due to additional buffering). > > Check that the domain 0 kernel you are using has the appropriate drivers > for your hardware. It''s probably using PIO or something daft.I had exactly this problem because the drivers for various IDE chipsets are missing in the default xen0 config. When I added the VIA 82cxxx driver back into the config, performance returned to normal (i.e. went from ~4MB/sec to ~38MB/sec in hdparm). It might be worth enabling the various IDE drivers in the standard configuration as I also tripped up over the fact the PDC 202xx driver was missing when I tried Xen on another machine. It wouldn''t boot until I used a xen0 kernel with that driver included. Regards, Leigh. ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Thanks guys for your help I will inspect the driver configuration in my system & get back. On using hdparm is found out that DMA is disabled by default in Xen (it was enabled on baseline) & I probably need to rebulid the kernel with this option turned on. If there are any other ways to turn on this option, please let me know Thanks Nauzad On Tue, 11 Jan 2005 19:11:53 -0000, Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk> wrote:> > Check that the domain 0 kernel you are using has the appropriate drivers > for your hardware. It''s probably using PIO or something daft. > > > I ask since it should be almost *impossible* to get anything more > > than a very small % slowdown on disk I/O unless things are very > > broken -- most of our benchmarks to date show 0% slowdown (and > > in some cases involving domU, a speedup due to additional buffering). > > Ian >------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Nauzad Sadry wrote:> On using hdparm is found out that DMA is disabled by default in Xen > (it was enabled on baseline) & I probably need to rebulid the kernel > with this option turned on. > > If there are any other ways to turn on this option, please let me knowas Ian already said, you''ll have to include your IDE chipset''s driver into kernel. It is located under Device drivers->ATA/ATAPI/MFM/RLL support. -jkt -- cd /local/pub && more beer > /dev/mouth ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Hello folks On turning DMA on in XEN kernel I managed to achieve file i/o performance comparable to baseline Thanks for your help Nauzad On Tue, 11 Jan 2005 23:15:55 +0100, Jan Kundrát <jan.kundrat@fzu.cz> wrote:> Nauzad Sadry wrote: > > On using hdparm is found out that DMA is disabled by default in Xen > > (it was enabled on baseline) & I probably need to rebulid the kernel > > with this option turned on. > > > > If there are any other ways to turn on this option, please let me know > > as Ian already said, you''ll have to include your IDE chipset''s driver > into kernel. It is located under Device drivers->ATA/ATAPI/MFM/RLL support. > > -jkt > > -- > cd /local/pub && more beer > /dev/mouth > >------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel