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Diffstat (limited to 'open_issues/xen_lseek.mdwn')
| -rw-r--r-- | open_issues/xen_lseek.mdwn | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/open_issues/xen_lseek.mdwn b/open_issues/xen_lseek.mdwn new file mode 100644 index 00000000..accc7c8f --- /dev/null +++ b/open_issues/xen_lseek.mdwn @@ -0,0 +1,35 @@ +[[!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]]. |