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author | https://me.yahoo.com/a/g3Ccalpj0NhN566pHbUl6i9QF0QEkrhlfPM-#b1c14 <diana@web> | 2015-02-16 20:08:03 +0100 |
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committer | GNU Hurd web pages engine <web-hurd@gnu.org> | 2015-02-16 20:08:03 +0100 |
commit | 95878586ec7611791f4001a4ee17abf943fae3c1 (patch) | |
tree | 847cf658ab3c3208a296202194b16a6550b243cf /open_issues/xen_lseek.mdwn | |
parent | 8063426bf7848411b0ef3626d57be8cb4826715e (diff) | |
download | web-95878586ec7611791f4001a4ee17abf943fae3c1.tar.gz web-95878586ec7611791f4001a4ee17abf943fae3c1.tar.bz2 web-95878586ec7611791f4001a4ee17abf943fae3c1.zip |
rename open_issues.mdwn to service_solahart_jakarta_selatan__082122541663.mdwn
Diffstat (limited to 'open_issues/xen_lseek.mdwn')
-rw-r--r-- | open_issues/xen_lseek.mdwn | 57 |
1 files changed, 0 insertions, 57 deletions
diff --git a/open_issues/xen_lseek.mdwn b/open_issues/xen_lseek.mdwn deleted file mode 100644 index 756abf5e..00000000 --- a/open_issues/xen_lseek.mdwn +++ /dev/null @@ -1,57 +0,0 @@ -[[!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, 2011-09-01: - - <youpi> hum, f951 does myriads of 71->io_seek_request (32768 0) = 0 32768 - <youpi> no wonder it's slow - <youpi> unfortunately that's also what it does on linux, the system call is - just less costly - <youpi> apparently gfortran calls io_seek for, like, every token of the - sourced file - <youpi> (fgetpos actually, but that's the same) - <youpi> and it is indeed about 10 times slower under Xen for some reason - -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]]. - -Also see the simple testcases [[test-lseek.c]] and [[test-mach.c]]. - -IRC, freenode, #hurd, 2011-11-05: - - <youpi> [test-mach.c is] mostly as a reference for the trap overhead - <youpi> 0.56µs (xen) vs 0.48µs(kvm) on test-mach - <youpi> 455µs(xen) vs 16µs(kvm) on test-lseek - <youpi> that might simply be an issue in the RPC mechanism, which behaves - badly with the xen memory management - <youpi> yes, about 0.5ms for an lseek, that's quite high :) |