Messages in this thread Patch in this message | | | Subject | Re: Plumbers: Tweaking scheduler policy micro-conf RFP | From | Joe Perches <> | Date | Wed, 23 May 2012 08:43:58 -0700 |
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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 $ 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)
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.
btw: There's still the unnecessary static DEFINE_PER_CPU(int, printk_pending); but the code is more involved around that one.
printk.c needs some refactoring and modularization, it's pretty ugly right now.
diff --git a/kernel/printk.c b/kernel/printk.c index 32462d2..3bd9a11 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -1734,16 +1734,21 @@ int is_console_locked(void) #define PRINTK_PENDING_SCHED 0x02 static DEFINE_PER_CPU(int, printk_pending); -static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf); + +#ifdef CONFIG_PRINTK +static DEFINE_PER_CPU(char[PRINTK_BUF_SIZE], printk_sched_buf); +#endif void printk_tick(void) { if (__this_cpu_read(printk_pending)) { int pending = __this_cpu_xchg(printk_pending, 0); +#ifdef CONFIG_PRINTK if (pending & PRINTK_PENDING_SCHED) { char *buf = __get_cpu_var(printk_sched_buf); printk(KERN_WARNING "[sched_delayed] %s", buf); } +#endif if (pending & PRINTK_PENDING_WAKEUP) wake_up_interruptible(&log_wait); }
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