On 27-Apr-13, at 5:53 PM, Helge Deller wrote:
On 04/27/2013 12:30 AM, Helge Deller wrote:
* James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>:
On Wed, 2013-04-24 at 09:33 +0200, Helge Deller wrote:
On 04/23/2013 10:22 PM, Helge Deller wrote:
commit e4e1e78facf7565cada909a69c7fb6415b6e7b83
Author: Helge Deller <deller@xxxxxx>
Date: Tue Apr 23 17:19:37 2013 +0200
parisc: increase kernel stack size to 32k
--- a/arch/parisc/include/asm/thread_info.h
+++ b/arch/parisc/include/asm/thread_info.h
-#define THREAD_SIZE_ORDER 2
+#define THREAD_SIZE_ORDER 3 /* 32k stack */
I tested again, and it actually needs to be 64k stacks to not
crash any longer.
So, the right temporary fix is:
+#define THREAD_SIZE_ORDER 4 /* 64k stack */
Will send updated patch soon.
This is an indicator of something seriously wrong somewhere. We've
always had the 16k stack just because of our large frames. In
theory,
the IRQ stack should only be the same size as the kernel stack, so
if we
have both in the same place, we should only need at max 32k ... if
we're
still seeing problems related to stack overrun, then it might be
we have
an IRQ recursion where we shouldn't have. To be honest, I have a
hard
time explaining why our stacks should be over 8k.
Attached is a new version of my irq-stack-patch, which made my
system really stable :-)
As test I did used "hackbench 300" (from the LTP project) which
created 12000 threads:
uptime: 23:44:09 up 17 min, 2 users, load average: 1232.23,
2966.09, 2466.39
My findings so far:
* kernel stack: THREAD_SIZE_ORDER needs to be at least 2 (=16k). x86
has 1 (8k).
With 8k kernel stacks and DEBUG_STACKOVERFLOW enabled, I get
directly after bootup:
stackcheck: swapper/0 has overflown a kernel stack (sp:bfc52030, stk
bottom-top:bfc50000-bfc52000)
* IRQ stack: 16k seems sufficient as well.
So, the combination of 16k kernel stack and 16k irq stacks seems OK.
I still need to clean up my patch, test if backtraces still work
(with which I currently
have problems) and prepare a final patch.
So far, I haven't been able to break the first version of the irqstack
patch. It's working far better than
setting THREAD_SIZE_ORDER to 4. There were various application errors
with the latter. Building
new version.
I have the following comments:
+#define get_current_sp(sp) __asm__("copy %%r30, %0" : "=r"(sp))
Probably, should be __asm__ __volatile__. I'm not sure that all changes
to the stack pointer are known to GCC.
+/* void call_on_stack(unsigned long param1, void *func, unsigned long
new_stack) */
+ENTRY(call_on_stack)
+ STREG %sp, 8(%arg2)
+ STREG %rp, 16(%arg2)
+
+ /* HPPA calling convention for function pointers */
+#ifdef CONFIG_64BIT
+ LDREG 16(%arg1), %arg1
+ bve,l (%arg1), %rp
+ addi 0x40, %arg2, %sp
+#else
+ addi 0x40, %arg2, %sp
+ be,l 0(%sr4,%arg1), %sr0, %r31
+ copy %r31, %rp
+#endif
+
+ addi -0x40, %sp, %sp
+ LDREG 16(%sp),%rp
+ bv (%rp)
+ LDREG 8(%sp),%sp
+ENDPROC(call_on_stack)
This doesn't full adhere to calling conventions but may work in
limited circumstances. For
example, 64-bit calls nominally require setup of the argument
pointer. There's also save
and restore of the PIC register if it can be modified.
Dave
--
John David Anglin dave.anglin@xxxxxxxx
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