Why should this class only available for kernel threads? There are
daemons ported from micro kernel platforms which act like a kernel
daemon but run in user land and could benefit from such a scheduler
class.
On Wed, Nov 11, 2009 at 1:00 AM, Darren J Moffat
<darrenm at sac.sfbay.sun.com> wrote:
> I'm submitting this as closed approved automatic, it has already been
> reviewed by core ZFS and kernel scheduling teams. Given the taxonomy
> of the new interfaces I believe this is sufficient review and closed
> approved automatic is sufficient. If any member disagrees then I'll
> set a fast-track timer.
>
> Template Version: @(#)sac_nextcase 1.68 02/23/09 SMI
> This information is Copyright 2009 Sun Microsystems
> 1. Introduction
> 1.1. Project/Component Working Name:
> System Duty Cycle Scheduling Class and ZFS IO Observability
> 1.2. Name of Document Author/Supplier:
> Author: Jonathan Adams
> 1.3 Date of This Document:
> 10 November, 2009
> 4. Technical Description
>
> This case covers two user-visible changes associated with the bug:
>
> 6806882 need a less brutal I/O scheduler
>
> The changes are:
>
> 1. A new kernel-thread-only scheduling class, SDC
> (System Duty Cycle) is introduced. Since the
> list of scheduling classes is user-visible through
> dispadmin(1M) and priocntl(1), we feel an ARC case
> is appropriate.
>
> The new scheduling class is only used by kernel threads,
> so the only manpage changes are a new SDC(7) page covering
> the existence of the new loadable module, and an update
> to the discussion of the SYS class in priocntl(2).
>
> A new function "sysdc_thread_enter()", puts a kernel thread
> into SDC.
>
> 2. In order to improve the observability of ZFS IO processing,
> we introduce a new system process per-zpool, with a
> u_comm and u_psargs of zpool-<poolname> (i.e. zpool-foo).
> The LWPs in the process are kernel threads associated
> with IO processing. Since these threads have LWPs, they
> get microstate accounting data. Thus, CPU usage associated
> with IO processing can be observed using prstat(1M) and ps(1).
>
> This process will always be in the global zone, even if
> the pool was imported into a local zone.
>
> These changes, while user-visible, are essentially implementation
> details, and are not committed interfaces. We've tried to make this
> clear in the manpage changes.
>
>
> Interface Table
> ---------------
>
> Interface Stability
> --------------------------------------- -----------------
> SDC module and scheduling class Consolidation Private
> sysdc_thread_enter() Consolidation Private
> zpool-<poolname> process Volatile
>
> We seek Micro/Patch binding for these interfaces.
>
> See Also
> --------
>
> 6806882 need a less brutal I/O scheduler
>
>
> Man Page Diffs
> --------------
>
> SDC(7)
> +Device and Network Interfaces SDC(7)
> +
> +
> +NAME
> + SDC - System Duty Cycle scheduling class
> +
> +DESCRIPTION
> + The System Duty Cycle (SDC) scheduling class is used for some
> + CPU-intensive kernel thread workloads. Like the SYS class,
> + it cannot be used for user processes.
> +
> +ATTRIBUTES
> + See attributes(5) for descriptions of the following attri-
> + butes:
> + ____________________________________________________________
> + | ATTRIBUTE TYPE | ATTRIBUTE VALUE |
> + |_____________________________|_____________________________|
> +
> +SEE ALSO
> + attributes(5)
> +
>
> priocntl(2)
> ...
> that class and/or when setting class-specific scheduling
> parameters.
>
> Two special scheduling classes, SYS and SDC, exist for the purpose of
> |
> scheduling the execution of certain special system processes
> (such as the swapper process). It is not possible to change
> the class of any LWP to SYS or SDC. In addition, any processes in
> |
> the SYS or SDC classes that are included in a specified set of
> |
> processes are disregarded by priocntl(). For example, an
> idtype of P_UID and an id value of 0 would specify all
> processes with a user ID of 0 except processes in the SYS and
> |
> SDC classes and (if changing the parameters using PC_SETPARMS or
> |
> PC_SETXPARMS) the init(1M) process.
> ...
>
> zpool(1M)
> --- zpool.1m.dist Tue Nov 3 14:00:53 2009
> +++ zpool.1m Tue Nov 3 14:49:47 2009
> @@ -947,6 +947,15 @@
> version number, and only up to the most
> recent version supported by this software.
>
> +PROCESSES
> + Each imported pool has an associated process, named
> + zpool-poolname. The threads in this process are the
> + pool's IO processing threads, which handle the compression,
> + checksumming, and other tasks for all IO associated with the
> + pool. This process exists to provides visibility into the CPU
> + utilization of the system's storage pools. The existence
> + of this process is an unstable interface.
> +
> EXAMPLES
> Example 1 Creating a RAID-Z Storage Pool
>
>
> 6. Resources and Schedule
> 6.4. Steering Committee requested information
> 6.4.1. Consolidation C-team Name:
> On
> 6.5. ARC review type: Automatic
> 6.6. ARC Exposure: open
>
> _______________________________________________
> opensolaris-arc mailing list
> opensolaris-arc at opensolaris.org
>
--
, _ _ ,
{ \/`o;====- Olga Kryzhanovska -====;o`\/ }
.----'-/`-/ olga.kryzhanovska at gmail.com \-`\-'----.
`'-..-| / Solaris/BSD//C/C++ programmer \ |-..-'`
/\/\ /\/\
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