Re: Plumbers: Tweaking scheduler policy micro-conf RFP

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

On Sun, May 20, 2012 at 6:55 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Sat, 2012-05-19 at 10:08 -0700, Linus Torvalds wrote:
>> Ingo, please don't take any of these patches if they are starting to
>> make NUMA scheduling be some arch-specific crap.
> I think there's a big mis-understanding here. I fully 100% agree with
> you on that. And this thread in particular isn't about NUMA at all.
> This thread is about modifying the arch interface of describing the
> chip.
> The current interface is we have 4 fixed topology domains:
>  SMT
>  MC
>  CPU
> (and the NUMA stuff comes on top of that and I just removed arch bits
> from that, so lets leave that for now).
> The first 3 domains depend on CONFIG_SCHED_{SMT,MC,BOOK} resp. and if an
> architecture select one of those it will have to provide a function
> cpu_{smt,coregroup,book}_mask and optionally put a struct sched_domain
> initializer in their asm/topology.h.
> Now I've had quite a few complaints from arch maintainers that the
> sched_domain initializer is a far too unwieldy interface to fill out and
> I quite agree with them.
> Now all I've meant to propose in this thread is to replace the entire
> above with a simpler interface.
> Instead of the above all I'm asking of doing is providing something
> along the lines of:
> struct sched_topology arch_topology[] = {
>        { cpu_smt_mask, ST_SMT },
>        { cpu_llc_mask, ST_CACHE },
>        { cpu_socket_mask, ST_SOCKET },
>        { NULL, },
> };
> and that's just about all an arch would need to do.
> That said, there are a few new things in ARM land like the big-little
> stuff that have no direct relation to anything on the x86 side. And they
> would very much like to have means of describing their chip topology as
> well.
> About power aware scheduling, yes its all a big mess and the current
> stuff is horrid and broken.
> That said, I do believe we can do better than nothing about it, and I'm
> really not asking for anything perfect -- in fact I'm asking for pretty
> much the same thing you are, something simple and understandable.
> The simple pack stuff on a minimum amount of power-gated units instead
> of spreading it out should get some benefit. For this we'd need to know
> at what granularity a chip can power-gate.
>> I'm very very serious about this. Try to make the scheduler have a
>> *simple* model that people can actually understand. For example, maybe
>> it can literally be a multi-level balancing thing, where the per-cpu
>> runqueues are grouped into a "shared core resources" balancer that
>> balances within the SMT or shared-L2 domain. And then there's an
>> upper-level balancer (that runs much more seldom) that is written to
>> balances within the socket. And then one that balances within the
>> node/board. And finally one that balances across boards.
> That is basically how the scheduler is set up. These are the
> sched_domains.
> There is an awful lot of complexity in that code though, and I've been
> trying to clean some of that up but its very slow going.
> The purpose of this thread is to both simplify and allow people to more
> easily express what they really care about. For this we need to explore
> the problem space.
> I know I haven't replied to all your points, and I suspect many are
> related to annoyances you might have from other threads and I shall
> attempt to answer them later.
> I do feel bad that I've managed to annoy you to such a degree though. I
> really would rather have a much simpler load-balancer too.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at
> Please read the FAQ at

Still you are just trying to said that your code is not bloated?
Up to over 500K for a cpu scheduler. Laughing
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at

[Other Archives]     [Linux Kernel Newbies]     [Linux Driver Development]     [Fedora Kernel]     [Linux Kernel Testers]     [Linux SH]     [Linux Omap]     [Linux Kbuild]     [Linux Tape]     [Linux Input]     [Linux Kernel Janitors]     [Linux Kernel Packagers]     [Linux Doc]     [Linux Man Pages]     [Linux API]     [Linux Memory Management]     [Linux Modules]     [Linux Standards]     [Kernel Announce]     [Netdev]     [Git]     [Linux PCI]     Linux CAN Development     [Linux I2C]     [Linux RDMA]     [Linux NUMA]     [Netfilter]     [Netfilter Devel]     [SELinux]     [Bugtraq]     [FIO]     [Linux Perf Users]     [Linux Serial]     [Linux PPP]     [Linux ISDN]     [Linux Next]     [Kernel Stable Commits]     [Linux Tip Commits]     [Kernel MM Commits]     [Linux Security Module]     [AutoFS]     [Filesystem Development]     [Ext3 Filesystem]     [Linux bcache]     [Ext4 Filesystem]     [Linux BTRFS]     [Linux CEPH Filesystem]     [Linux XFS]     [XFS]     [Linux NFS]     [Linux CIFS]     [Ecryptfs]     [Linux NILFS]     [Linux Cachefs]     [Reiser FS]     [Initramfs]     [Linux FB Devel]     [Linux OpenGL]     [DRI Devel]     [Fastboot]     [Linux RT Users]     [Linux RT Stable]     [eCos]     [Corosync]     [Linux Clusters]     [LVS Devel]     [Hot Plug]     [Linux Virtualization]     [KVM]     [KVM PPC]     [KVM ia64]     [Linux Containers]     [Linux Hexagon]     [Linux Cgroups]     [Util Linux]     [Wireless]     [Linux Bluetooth]     [Bluez Devel]     [Ethernet Bridging]     [Embedded Linux]     [Barebox]     [Linux MMC]     [Linux IIO]     [Sparse]     [Smatch]     [Linux Arch]     [x86 Platform Driver]     [Linux ACPI]     [Linux IBM ACPI]     [LM Sensors]     [CPU Freq]     [Linux Power Management]     [Linmodems]     [Linux DCCP]     [Linux SCTP]     [ALSA Devel]     [Linux USB]     [Linux PA RISC]     [Linux Samsung SOC]     [MIPS Linux]     [IBM S/390 Linux]     [ARM Linux]     [ARM Kernel]     [ARM MSM]     [Tegra Devel]     [Sparc Linux]     [Linux Security]     [Linux Sound]     [Linux Media]     [Video 4 Linux]     [Linux IRDA Users]     [Linux for the blind]     [Linux RAID]     [Linux ATA RAID]     [Device Mapper]     [Linux SCSI]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Linux IDE]     [Linux SMP]     [Linux AXP]     [Linux Alpha]     [Linux M68K]     [Linux ia64]     [Linux 8086]     [Linux x86_64]     [Linux Config]     [Linux Apps]     [Linux MSDOS]     [Linux X.25]     [Linux Crypto]     [DM Crypt]     [Linux Trace Users]     [Linux Btrace]     [Linux Watchdog]     [Utrace Devel]     [Linux C Programming]     [Linux Assembly]     [Dash]     [DWARVES]     [Hail Devel]     [Linux Kernel Debugger]     [Linux gcc]     [Gcc Help]     [X.Org]     [Wine]

Add to Google Powered by Linux

[Older Kernel Discussion]     [Yosemite National Park Forum]     [Large Format Photos]     [Gimp]     [Yosemite Photos]     [Stuff]