From 3e7472b3d54853389cd8a17475901fbef976ef18 Mon Sep 17 00:00:00 2001 From: Thomas Schwinge Date: Thu, 1 Sep 2011 09:27:33 +0200 Subject: IRC. --- open_issues/performance/degradation.mdwn | 28 +++++++++++++ .../performance/io_system/binutils_ld_64ksec.mdwn | 15 +++++++ .../performance/microkernel_multi-server.mdwn | 47 ++++++++++++++++++++++ 3 files changed, 90 insertions(+) create mode 100644 open_issues/performance/degradation.mdwn create mode 100644 open_issues/performance/microkernel_multi-server.mdwn (limited to 'open_issues/performance') diff --git a/open_issues/performance/degradation.mdwn b/open_issues/performance/degradation.mdwn new file mode 100644 index 00000000..5db82e31 --- /dev/null +++ b/open_issues/performance/degradation.mdwn @@ -0,0 +1,28 @@ +[[!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]]."]]"""]] + +[[!meta title="Degradation of GNU/Hurd ``system performance''"]] + +Email, *id:"87mxg2ahh8.fsf@kepler.schwinge.homeip.net"* (bug-hurd, 2011-07-25, +Thomas Schwinge) + +> Building a certain GCC configuration on a freshly booted system: 11 h. +> Remove build tree, build it again (2nd): 12 h 50 min. Huh. Remove build +> tree, reboot, build it again (1st): back to 11 h. Remove build tree, build +> it again (2nd): 12 h 40 min. Remove build tree, build it again (3rd): 15 h. + +IRC, freenode, #hurd, 2011-07-23 + + < antrik> tschwinge: yes, the system definitely gets slower with + time. after running for a couple of weeks, it needs at least twice as + long to open a new shell for example + < antrik> I don't know whether this is only related to swap usage, or there + are some serious fragmentation issues + < braunr> antrik: both could be induced by fragmentation diff --git a/open_issues/performance/io_system/binutils_ld_64ksec.mdwn b/open_issues/performance/io_system/binutils_ld_64ksec.mdwn index 79c2300f..359d5fee 100644 --- a/open_issues/performance/io_system/binutils_ld_64ksec.mdwn +++ b/open_issues/performance/io_system/binutils_ld_64ksec.mdwn @@ -33,3 +33,18 @@ the testee shows that (primarily) an ever-repeating series of `io_seek` and `io_read` is being processed. Running the testee on GNU/Linux with strace shows the equivalent thing (`_llseek`, `read`) -- but Linux' I/O system isn't as slow as the Hurd's. + +--- + +IRC, freenode, #hurd, 2011-09-01: + + hum, f951 does myriads of 71->io_seek_request (32768 0) = 0 32768 + no wonder it's slow + unfortunately that's also what it does on linux, the system call is + just less costly + apparently gfortran calls io_seek for, like, every token of the + sourced file + (fgetpos actually, but that's the same) + and it is indeed about 10 times slower under Xen for some reason + +[[!tag open_issue_xen]] diff --git a/open_issues/performance/microkernel_multi-server.mdwn b/open_issues/performance/microkernel_multi-server.mdwn new file mode 100644 index 00000000..111d2b88 --- /dev/null +++ b/open_issues/performance/microkernel_multi-server.mdwn @@ -0,0 +1,47 @@ +[[!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_documentation]] + +Performance issues due to the microkernel/multi-server system architecture? + +IRC, freenode, #hurd, 2011-07-26 + + < CTKArcher> I read that, because of its microkernel+servers design, the + hurd was slower than a monolithic kernel, is that confirmed ? + < youpi> the hurd is currently slower than current monolithic kernels, but + it's not due to the microkernel + servers design + < youpi> the microkernel+servers design makes the system call path longer + < youpi> but you're bound by disk and network speed + < youpi> so the extra overhead will not hurt so much + < youpi> except dumb applications keeping doing system calls all the time + of course, but they are usually considered bogus + < braunr> there may be some patterns (like applications using pipes + extensively, e.g. git-svn) which may suffer from the design, but still in + an acceptable range + < CTKArcher> so, you are saying that disk and network are more slowing the + system than the longer system call path and because of that, it wont + really matter ? + < youpi> braunr: they should sitll be fixed because they'll suffer (even if + less) on monolithic kernels + < youpi> CTKArcher: yes + < braunr> yes + < CTKArcher> mmh + < youpi> CTKArcher: you might want to listen to AST's talk at fosdem 10 + iirc, about minix + < youpi> they even go as far as using an IPC for each low-level in/out + < youpi> for security + < braunr> this has been expected for a long time + < braunr> which is what motivated research in microkernels + < CTKArcher> I've already downloaded the video :) + < youpi> and it has been more and more true with faster and faster cpus + < braunr> but in 95, processors weren't that fast compared to other + components as they are now + < youpi> while disk/mem haven't evovled so fast -- cgit v1.2.3