| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <tip-0d9ba8b03cfaed2696de42fe15ed410ba2ec7dbe@git.kernel.org> Date: Tue, 16 Sep 2014 03:57:03 -0700 From: tip-bot for Juri Lelli <tipbot@...or.com> To: linux-tip-commits@...r.kernel.org Cc: linux-kernel@...r.kernel.org, luca.abeni@...tn.it, hpa@...or.com, mingo@...nel.org, henrik@...tad.us, torvalds@...ux-foundation.org, peterz@...radead.org, rdunlap@...radead.org, raistlin@...ux.it, juri.lelli@....com, tglx@...utronix.de, juri.lelli@...il.com Subject: [tip:sched/core] Documentation/scheduler/sched-deadline.txt: Rewrite section 4 intro Commit-ID: 0d9ba8b03cfaed2696de42fe15ed410ba2ec7dbe Gitweb: http://git.kernel.org/tip/0d9ba8b03cfaed2696de42fe15ed410ba2ec7dbe Author: Juri Lelli <juri.lelli@....com> AuthorDate: Tue, 9 Sep 2014 10:57:13 +0100 Committer: Ingo Molnar <mingo@...nel.org> CommitDate: Tue, 16 Sep 2014 10:23:01 +0200 Documentation/scheduler/sched-deadline.txt: Rewrite section 4 intro Section 4 intro was still describing the old interface. Rewrite it. Signed-off-by: Juri Lelli <juri.lelli@....com> Signed-off-by: Luca Abeni <luca.abeni@...tn.it> Reviewed-by: Henrik Austad <henrik@...tad.us> Cc: Randy Dunlap <rdunlap@...radead.org> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Dario Faggioli <raistlin@...ux.it> Cc: Juri Lelli <juri.lelli@...il.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Link: http://lkml.kernel.org/r/1410256636-26171-3-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar <mingo@...nel.org> --- Documentation/scheduler/sched-deadline.txt | 51 +++++++++++++++--------------- 1 file changed, 25 insertions(+), 26 deletions(-) diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt index a029891..f75d832 100644 --- a/Documentation/scheduler/sched-deadline.txt +++ b/Documentation/scheduler/sched-deadline.txt @@ -165,39 +165,38 @@ CONTENTS In order for the -deadline scheduling to be effective and useful, it is important to have some method to keep the allocation of the available CPU - bandwidth to the tasks under control. - This is usually called "admission control" and if it is not performed at all, - no guarantee can be given on the actual scheduling of the -deadline tasks. - - Since when RT-throttling has been introduced each task group has a bandwidth - associated, calculated as a certain amount of runtime over a period. - Moreover, to make it possible to manipulate such bandwidth, readable/writable - controls have been added to both procfs (for system wide settings) and cgroupfs - (for per-group settings). - Therefore, the same interface is being used for controlling the bandwidth - distrubution to -deadline tasks. - - However, more discussion is needed in order to figure out how we want to manage - SCHED_DEADLINE bandwidth at the task group level. Therefore, SCHED_DEADLINE - uses (for now) a less sophisticated, but actually very sensible, mechanism to - ensure that a certain utilization cap is not overcome per each root_domain. - - Another main difference between deadline bandwidth management and RT-throttling + bandwidth to the tasks under control. This is usually called "admission + control" and if it is not performed at all, no guarantee can be given on + the actual scheduling of the -deadline tasks. + + The interface used to control the fraction of CPU bandwidth that can be + allocated to -deadline tasks is similar to the one already used for -rt + tasks with real-time group scheduling (a.k.a. RT-throttling - see + Documentation/scheduler/sched-rt-group.txt), and is based on readable/ + writable control files located in procfs (for system wide settings). + Notice that per-group settings (controlled through cgroupfs) are still not + defined for -deadline tasks, because more discussion is needed in order to + figure out how we want to manage SCHED_DEADLINE bandwidth at the task group + level. + + A main difference between deadline bandwidth management and RT-throttling is that -deadline tasks have bandwidth on their own (while -rt ones don't!), - and thus we don't need an higher level throttling mechanism to enforce the - desired bandwidth. + and thus we don't need a higher level throttling mechanism to enforce the + desired bandwidth. Therefore, using this simple interface we can put a cap + on total utilization of -deadline tasks (i.e., \Sum (runtime_i / period_i) < + global_dl_utilization_cap). 4.1 System wide settings ------------------------ The system wide settings are configured under the /proc virtual file system. - For now the -rt knobs are used for dl admission control and the -deadline - runtime is accounted against the -rt runtime. We realise that this isn't - entirely desirable; however, it is better to have a small interface for now, - and be able to change it easily later. The ideal situation (see 5.) is to run - -rt tasks from a -deadline server; in which case the -rt bandwidth is a direct - subset of dl_bw. + For now the -rt knobs are used for -deadline admission control and the + -deadline runtime is accounted against the -rt runtime. We realise that this + isn't entirely desirable; however, it is better to have a small interface for + now, and be able to change it easily later. The ideal situation (see 5.) is to + run -rt tasks from a -deadline server; in which case the -rt bandwidth is a + direct subset of dl_bw. This means that, for a root_domain comprising M CPUs, -deadline tasks can be created while the sum of their bandwidths stays below: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists