lkml.org 
[lkml]   [2012]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Plumbers: Tweaking scheduler policy micro-conf RFP

    * Joe Perches <joe@perches.com> wrote:

    > On Wed, 2012-05-23 at 17:03 +0200, Ingo Molnar wrote:
    > > * Chen <hi3766691@gmail.com> wrote:
    > >
    > > > Still you are just trying to said that your code is not bloated?
    > > > Up to over 500K for a cpu scheduler. Laughing
    > >
    > > Where did you get that 500K from? You are off from the truth
    > > almost by an order of magnitude.
    > >
    > > Here's the scheduler size on Linus's latest tree, on 64-bit
    > > defconfig's:
    > >
    > > $ size kernel/sched/built-in.o
    > > text data bss dec hex filename
    > > 83611 10404 2524 96539 1791b kernel/sched/built-in.o
    > >
    > > That's SMP+NUMA, i.e. everything included.
    > >
    > > The !NUMA !SMP UP scheduler, if you are on a size starved
    > > ultra-embedded device, is even smaller, just 22K:
    > >
    > > $ size kernel/sched/built-in.o
    > > text data bss dec hex filename
    > > 19882 2218 148 22248 56e8 kernel/sched/built-in.o
    >
    > Here's an allyesconfig x86-32

    allyesconfig includes a whole lot of debugging code so it's a
    pretty meaningless size test.

    > $ size kernel/sched/built-in.o
    > text data bss dec hex filename
    > 213892 10856 65832 290580 46f14 kernel/sched/built-in.o
    >
    > But that's not the only sched related code.
    >
    > In a 1000 cpu config, there also an extra 500+ bytes per cpu
    > in printk (I don't think that's particularly important btw)

    A 1000 cpu piece of hardware will have a terabyte of RAM or
    more. 0.5K per CPU is reasonable.

    > kernel/printk.c adds:
    >
    > static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
    >
    > Maybe #ifdefing this when !CONFIG_PRINTK would reduce size
    > a little in a few cases. I've attached a trivial suggested patch.

    That might make sense for the ultra-embedded.

    Still 500K is an obviously nonsensical number.

    Thanks,

    Ingo


    \
     
     \ /
      Last update: 2012-05-23 19:02    [W:0.046 / U:0.036 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site