User: Password:
Subscribe / Log in / New account

Various scheduler-related topics

Various scheduler-related topics

Posted Sep 17, 2009 15:11 UTC (Thu) by jimparis (subscriber, #38647)
In reply to: Various scheduler-related topics by hppnq
Parent article: Various scheduler-related topics

Linus' comment at the time:
> We've invalidated the TLB anyway due to the page table copy
seems to contradict one point in this current article:
> .. the translation lookaside buffer (TLB) contains the right information, etc.
Unless things have changed in 8 years, of course.

(Log in to post comments)

Various scheduler-related topics

Posted Sep 18, 2009 7:12 UTC (Fri) by mingo (subscriber, #31122) [Link]

Unless things have changed in 8 years, of course.

Two fundamental things have changed.

Firstly, we have an increase in parallelism on the hardware level (more hardware threads, more cores, more sockets) - so pushing child tasks away to other CPUs is generally a good idea.

Secondly, back then in the 2.4 heydays we also didnt have proper vfork() yet. vfork() will in essence guarantee child-runs-first via an explicit handshake between parent and the exec()-ing child. (regardless of the sysctl_sched_child_runs_first control.) That's faster and more efficient than any heuristics the scheduler can provide in this area.

Various scheduler-related topics

Posted Sep 24, 2009 8:33 UTC (Thu) by renox (subscriber, #23785) [Link]

Erm, the vfork manpage comment "It is rather unfortunate that Linux revived this spectre from the past." isn't very motivating for application developers to use vfork..

I think that the API is faulty here: whether it is forking or sending a message, the application developers know if they would prefer scheduling immediately the child/target process or not, so the API should allow the developer to say what he prefers instead of relying on one global default.

Various scheduler-related topics

Posted Sep 18, 2009 7:37 UTC (Fri) by Kamilion (subscriber, #42576) [Link]

Could be the whole SMP-gone-mainstream thing... ;)
The x86 architecture has gone through some interesting permutations since 2001.

*sigh* I remember kernel 2.4.4... Wrestling with going from Slink to Potato and ReiserFS in 2.4.6 going haywire... The install discs still have a warm place in my big CD binder of Linux CDs going back to The Linux System Administrator's Survival Guide's Slackware 3.0 pack-in from 1996.

We've come so far. B-tree filesystems (B+TRee now) are hip again, gentoo's visibly early console/splash work has paved the way for xsplash, 1.6ghz chips have become a hot item again, and we're finally at the point where 256GB SSDs are competing with the 250GB Hard Drives everyone was awestruck with years ago. Good times.

Copyright © 2017, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds