Andrew Morton wrote:
> Brian Gerst wrote:
>
>>These patches convert some of the existing arrays based on NR_CPUS to
>>use the new per cpu code.
>>
>
>
> Brian, I tested this patch (rediffed against 2.5.13, below)
> on the quad Xeon and it failed.
>
> The machine died when bringing up the secondary CPUs
> ("CPU#3 already started!" and "Unable to handle kernel...")
>
> I backed out the sched.c part and the machine booted. So
> I guess the secondary CPU bringup code uses the scheduler
> somehow.
>
> And again, the numbers in /proc/meminfo are whacko:
>
> LowFree: 94724 kB
> SwapTotal: 4000040 kB
> SwapFree: 3999700 kB
> Dirty: 7232 kB
> Writeback: 4294967264 kB
>
> Which never happens with the open-coded per-cpu accumulators.
> After a normal boot I see:
>
> LowFree: 95804 kB
> SwapTotal: 4000040 kB
> SwapFree: 3999940 kB
> Dirty: 1356 kB
> Writeback: 0 kB
>
>
> Now, it may be that some pages are being marked dirty before
> the per-cpu areas are set up, but there's no way in which
> any pages will have been marked for writeback by that time, so
> that "-32" value is definitely wrong.
>
> 'fraid I have to do a whine-and-run on this problem, but
> it does still appear that there is something fishy with
> the percpu infrastructure.
>
Andrew, could you try this patch? I suspect something in setup_arch()
is touching the per cpu area before it gets copied for the other cpus.
This patch makes certain the boot cpu area is setup ASAP.
--Brian Gerst
diff -urN linux-2.5.13/arch/i386/vmlinux.lds linux/arch/i386/vmlinux.lds --- linux-2.5.13/arch/i386/vmlinux.lds Thu Mar 7 21:18:16 2002 +++ linux/arch/i386/vmlinux.lds Sun May 5 11:46:26 2002 @@ -57,10 +57,13 @@ *(.initcall7.init) } __initcall_end = .; + . = ALIGN(32); __per_cpu_start = .; .data.percpu : { *(.data.percpu) } + . = ALIGN(32); __per_cpu_end = .; + . = ALIGN(4096); __init_end = .; @@ -70,6 +73,10 @@ . = ALIGN(32); .data.cacheline_aligned : { *(.data.cacheline_aligned) } + . = ALIGN(32); + __cpu0_data = .; + .data.cpu0 : { . += SIZEOF(.data.percpu); } + __bss_start = .; /* BSS */ .bss : { *(.bss) diff -urN linux-2.5.13/init/main.c linux/init/main.c --- linux-2.5.13/init/main.c Wed May 1 08:40:14 2002 +++ linux/init/main.c Sun May 5 12:27:38 2002 @@ -272,28 +272,40 @@ #define smp_init() do { } while (0) #endif +static inline void setup_boot_cpu_area(void) { } static inline void setup_per_cpu_areas(void) { } #else #ifdef __GENERIC_PER_CPU +/* Created by linker magic */ +extern char __per_cpu_start[], __per_cpu_end[], __cpu0_data[]; unsigned long __per_cpu_offset[NR_CPUS]; +static void __init setup_boot_cpu_area(void) +{ + unsigned long size; + + size = __per_cpu_end - __per_cpu_start; + if (!size) + return; + __per_cpu_offset[0] = __cpu0_data - __per_cpu_start; + memcpy(__cpu0_data, __per_cpu_start, size); +} + static void __init setup_per_cpu_areas(void) { unsigned long size, i; char *ptr; - /* Created by linker magic */ - extern char __per_cpu_start[], __per_cpu_end[]; /* Copy section for each CPU (we discard the original) */ - size = ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES); + size = __per_cpu_end - __per_cpu_start; if (!size) return; ptr = alloc_bootmem(size * NR_CPUS); - for (i = 0; i < NR_CPUS; i++, ptr += size) { + for (i = 1; i < NR_CPUS; i++, ptr += size) { __per_cpu_offset[i] = ptr - __per_cpu_start; memcpy(ptr, __per_cpu_start, size); } @@ -340,6 +352,7 @@ * enable them */ lock_kernel(); + setup_boot_cpu_area(); printk(linux_banner); setup_arch(&command_line); setup_per_cpu_areas();
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This archive was generated by hypermail 2b29 : Tue May 07 2002 - 22:00:24 EST