IRC.

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+[[!meta copyright="Copyright © 2011 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts.  A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+[[!tag open_issue_xen]]
+
+IRC, freenode, #hurd, 2011-11-02:
+
+    <youpi> btw, we have a performance issue with xen
+    <youpi> an lseek() call costs a huge lot
+    <youpi> like 1ms
+    <youpi> while the same costs just a few dozens µs with kvm
+    <youpi> there's of course the cost of switching between ring3, ring0,
+      ring1, ring0, ring3, but still
+    <gianluca> oh, nice.
+    <youpi> lseek is supposed to perform only a back&forth
+    <youpi> and I don't observe disk activity, so it's not waiting for the disk
+      to complete whatever atime change & such :)
+    <youpi> it was mentioned that perhaps xen in hvm mode with pv drivers would
+      be faster
+    <youpi> thanks to the ring3/"1" switching  being done by the processor
+    <youpi> (and assuming npt)
+    <gianluca> hm
+    <gianluca> i'll look into that, sounds fun.
+    <gianluca> :)
+    <tschwinge> Here is a testcase:
+      http://www.gnu.org/software/hurd/open_issues/performance/io_system/binutils_ld_64ksec.html
+
+[[performance/io_system/binutils_ld_64ksec]].