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VinzC
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Joined: 17 Apr 2004
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Location: Dark side of the mood
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 Posted: Thu Mar 17, 2011 4:30 pm Post subject: Kernel 2.6.38 really impresses! |
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Hi all.
I couldn't wait until 2.6.38 was available so I compiled it yesterday afternoon and tested it right away. I just had forgotten to recompile my ATI video driver but in the end it keeps its promises. I ran a -j16 make against glibc and gcc, ran a video through VLC and started a huge transfer through USB to my external disk. The video ran flawlessly without a hickup. I'm really pleased to see my desktop responsive again, almost like I never saw it (but I'd exaggerate  ).
Honestly, taste it, try it use it! It's worth the change. Be sure to check CONFIG_CGROUPS and CONFIG_CGROUP_SCHED in your kernel config for it's not enabled by default. I guess Pappy Mc Fae will have a very good time preparing a new seed for this kernel .
Cheers.
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leifbk
Guru
Joined: 05 Jan 2004
Posts: 425
Location: Bærum, Norway
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| Posted: Thu Mar 17, 2011 6:01 pm Post subject: Re: Kernel 2.6.38 really impresses! |
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| VinzC wrote: | Be sure to check CONFIG_CGROUPS and CONFIG_CGROUP_SCHED in your kernel config for it's not enabled by default.
Cheers. |
I'm running this kernel too, I've had gentoo-sources ~amd64 in my /etc/portage/package.keywords for some time, and 2.6.38 arrived yesterday, less than two days after it was announced by Linus. That's bleeding edge 
I can't find any CONFIG_CGROUP_SCHED. Do you mean CONFIG_SCHED_AUTOGROUP ?
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jms.gentoo
Tux's lil' helper
Joined: 07 May 2009
Posts: 102
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| Posted: Thu Mar 17, 2011 7:09 pm Post subject: |
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you only need to select
-> General setup
-->Automatic process group scheduling [CONFIG_SCHED_AUTOGROUP]
it will select automatically the rest
Selects: EVENTFD [=y] && CGROUPS [=y] && CGROUP_SCHED [=y] && FAIR_GROUP_SCHED [=y]
if you deselect CONFIG_SCHED_AUTOGROUP and go back to configure you will see these one
-> General setup
-->Control Group support[CONFIG_CGROUPS](CGROUPS )
--->Group CPU scheduler[CONFIG_CGROUP_SCHED](CGROUP_SCHED)
---->Group scheduling for SCHED_OTHER[FAIR_GROUP_SCHED]
Conclusion :to get the famous " 233-line pach " simply
select -> General setup
-->Automatic process group scheduling [CONFIG_SCHED_AUTOGROUP] (SCHED_AUTOGROUP)
and you're good to go |
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cach0rr0
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Joined: 13 Nov 2008
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Location: Houston, Republic of Texas
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| Posted: Thu Mar 17, 2011 7:18 pm Post subject: |
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i havent read up on this a ton - is this a CPU scheduling deal, IO scheduling, which?
mainly wondering if, come time to test out .38, I should pluck out BFS and go with this, or if this isn't a replacement, and is something else entirely
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bobspencer123
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| Posted: Thu Mar 17, 2011 7:22 pm Post subject: |
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Thanks for the update on this kernel. I will have to try it out. I wonder if this also fixes the fragmentation issue between nfs transfers and xfs?
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VoidMage
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| Posted: Thu Mar 17, 2011 8:22 pm Post subject: |
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| See git log entry for details. |
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Jaglover
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Ant P.
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| Posted: Fri Mar 18, 2011 1:32 am Post subject: |
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| Is this overhyped patch really so much better than the BFS I've been using for the past 18 months or so? I'm watching 720p video with a gcc -j32 compile on it right now. |
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cach0rr0
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| Posted: Fri Mar 18, 2011 2:57 am Post subject: |
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cheers for the link, interesting discussion they have going on.
having said that, I'm somewhat in Ant_P's same boat.
Sounds like heaps of hype, and while I *am* curious, things are working delightfully for me with BFS, I would be interested to see a compelling reason to make the change, rather, BFS is doing everything I need at the moment, and while I'm keen on squeezing out every last bit I can from this machine, if it's only a nominal gain, dunno, hard sell. I *am* glad mainline is starting to pay a bit more attention to interactivity requirements from desktop users, though, instead of just seeing if we can work efficiently with 4096 cores.
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wswartzendruber
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| Posted: Fri Mar 18, 2011 5:39 am Post subject: |
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| Wonder how long it'll take it to show up in hardened-sources. |
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printf
Tux's lil' helper
Joined: 02 Dec 2010
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| Posted: Fri Mar 18, 2011 6:06 am Post subject: |
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| usually how long it takes for at least gentoo-sources be unmasked with this kernel? |
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Anon-E-moose
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| Posted: Fri Mar 18, 2011 10:32 am Post subject: |
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Add me to the BFS has been giving me good performance camp, though I may try 2.6.38 sometime, I'll wait for further testing.
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VinzC
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Joined: 17 Apr 2004
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Location: Dark side of the mood
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| Posted: Fri Mar 18, 2011 4:13 pm Post subject: |
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| Ant_P wrote: | | Is this overhyped patch really so much better than the BFS I've been using for the past 18 months or so? I'm watching 720p video with a gcc -j32 compile on it right now. |
I wouldn't say overhyped  . IT deserved all the... «noise» there have been around. The tests I made allowed me to use my laptop as if it weren't stressed at all. Before I would have had to wait (especially with -j16) until compile was over. That's also why I had to decrease the -j value to 3 because compiling certain packages made my computer (Core2 Duo) totally unresponsive for seconds.
Those times are over!
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pilla
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| Posted: Fri Mar 18, 2011 4:26 pm Post subject: |
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Yes, it impressed me too. Xorg can't stop crashing on it 
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Gusar
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| Posted: Fri Mar 18, 2011 5:52 pm Post subject: |
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| Err, what's the point of using more than -j3 on a dual core machine? |
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PaulBredbury
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| Posted: Fri Mar 18, 2011 6:05 pm Post subject: |
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Meh, BFS is tons better, with:
| Code: | alias mplayer="ionice -c2 nice -n -4 /usr/bin/mplayer"
alias make='ionice -c3 schedtool -D -e /usr/bin/make' |
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Ant P.
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| Posted: Fri Mar 18, 2011 6:17 pm Post subject: |
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| Gusar wrote: | | Err, what's the point of using more than -j3 on a dual core machine? |
There is none, bar showing off. In fact -j3 itself is only needed because the vanilla scheduler has flaws; BFS on a dual core reaches peak efficiency at -j2. |
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NathanZachary
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| Posted: Sat Mar 19, 2011 3:41 am Post subject: |
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It seems that there is a problem with 2.6.38 though. udev won't build with it:
It seems that the problem is with videodev.h being removed from 2.6.38:
http://comments.gmane.org/gmane.linux.hotplug.devel/16670
The error I get on my new installation is:
| Code: |
extras/v4l_id/v4l_id.c:31:28: error: linux/videodev.h: No such file or directory
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There are other errors, but it fails to build (with or without the 'extra' USE flag).
Anyone have suggestions?
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d2_racing
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Joined: 25 Apr 2005
Posts: 13047
Location: Ste-Foy,Canada
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| Posted: Sat Mar 19, 2011 3:50 am Post subject: |
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I use this configuration :
| Code: |
General stuff
[*] Control Group support
[ ] Example debug cgroup subsystem
[*] Namespace cgroup subsystem
[*] Freezer cgroup subsystem
[*] Device controller for cgroups
[*] Cpuset support
[*] Include legacy /proc/<pid>/cpuset file
[ ] Simple CPU accounting cgroup subsystem
[ ] Resource counters
-*- Group CPU scheduler --->
<*> Block IO controller
[ ] Enable Block IO controller debugging
[*] Automatic process group scheduling
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graysky
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VinzC
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Joined: 17 Apr 2004
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Location: Dark side of the mood
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| Posted: Sat Mar 19, 2011 10:59 am Post subject: |
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| Gusar wrote: | | Err, what's the point of using more than -j3 on a dual core machine? |
There are plenty of such questions with GNU/Linux! And the answer would always be: «because I can!»
| NathanZachary wrote: | It seems that there is a problem with 2.6.38 though. udev won't build with it:
It seems that the problem is with videodev.h being removed from 2.6.38:[...]
Anyone have suggestions? |
I have udev-162 and it compiles fine. What version do you have?
| PaulBredbury wrote: | Meh, BFS is tons better, with:
| Code: | alias mplayer="ionice -c2 nice -n -4 /usr/bin/mplayer"
alias make='ionice -c3 schedtool -D -e /usr/bin/make' |
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The difference is 2.6.38 will automatically assign time slices without any overhead. I also used to renice (not the way you've shown, which I didn't know) but I found it boring in the end . Say 2.6.38 and AUTO_CGROUPS are for the lazy then .
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Gusar
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| Posted: Sat Mar 19, 2011 11:10 am Post subject: |
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| VinzC wrote: | | There are plenty of such questions with GNU/Linux! And the answer would always be: «because I can!» |
Which is a valid answer as such. But still, -j16 on a dual-core has no real value, it's ridiculous. And if this "miracle" patch only does something at a ridiculous setting, it's equally valid to question the "miracleness" (yes, that's a word! ) of it. |
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graysky
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| Posted: Sat Mar 19, 2011 11:34 am Post subject: |
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| Gusar wrote: | | VinzC wrote: | | There are plenty of such questions with GNU/Linux! And the answer would always be: «because I can!» |
Which is a valid answer as such. But still, -j16 on a dual-core has no real value, it's ridiculous. And if this "miracle" patch only does something at a ridiculous setting, it's equally valid to question the "miracleness" (yes, that's a word! ) of it. |
This is what Con argued. Why optimize a kernel to perform at insane workloads when 99.99 % of the user don't use their machines as such. |
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jcTux
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Joined: 29 Dec 2009
Posts: 276
Location: Tours, France
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| Posted: Sat Mar 19, 2011 11:59 am Post subject: |
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| NathanZachary wrote: | It seems that there is a problem with 2.6.38 though. udev won't build with it:
It seems that the problem is with videodev.h being removed from 2.6.38:
http://comments.gmane.org/gmane.linux.hotplug.devel/16670
The error I get on my new installation is:
| Code: |
extras/v4l_id/v4l_id.c:31:28: error: linux/videodev.h: No such file or directory
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There are other errors, but it fails to build (with or without the 'extra' USE flag).
Anyone have suggestions? |
Udev compiles fine here | Code: | | USE="extras -devfs-compat -old-hd-rules (-selinux) -test" |
| Code: | uname -r
2.6.38-gentoo |
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VinzC
Watchman
Joined: 17 Apr 2004
Posts: 5098
Location: Dark side of the mood
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| Posted: Sat Mar 19, 2011 12:59 pm Post subject: |
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| VinzC wrote: | | There are plenty of such questions with GNU/Linux! And the answer would always be: «because I can!» |
| Gusar wrote: | | Which is a valid answer as such. But still, -j16 on a dual-core has no real value, it's ridiculous. And if this "miracle" patch only does something at a ridiculous setting, it's equally valid to question the "miracleness" (yes, that's a word! ) of it. |
| graysky wrote: | | This is what Con argued. Why optimize a kernel to perform at insane workloads when 99.99 % of the user don't use their machines as such. |
Well, I really don't like percentages like this (i.e. what's this estimation based on?) but I agree with you: most GNU/Linux users won't probably load their system that much hence the impact of the patch is limited. But the main advantage is there's no longer a need to manually tweak performance using a command. It's handled automatically, which clueless users will probably appreciate.
OTOH -j16 was indeed for the sake of testing. Of course it makes no sense to raise that number that much. [I've compiled hugin and then I saw the effect: computer not responsive for a while, high latency, high I/O rate and much longer waits.] But instead of restoring -j3, I'll keep -j5 for a while and see.
Finally, even if this patch might happen to prove useless for a majority of users, it doubtlessly comes handy with Gentoo just because compiling is a common task. No need to renice, just compile as much as you want and watch. That's the point.
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Last edited by VinzC on Sat Mar 19, 2011 1:27 pm; edited 1 time in total |
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Kernel & Hardware
