lkml.org 
[lkml]   [1999]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch] releasing kernel lock during copy_from/to_user [Re: 2.3.3_andrea2 & 2.2.9_andrea1 [was Re: Bad apache perfomance wtih linux SMP]]
On Thu, 20 May 1999, Andrea Arcangeli wrote:

>taking a different way to achieve the same thing in a simpler way. I'll
>post a patch incremental with 2.3.3_andrea2.bz2 soon.

Here it is the patch against 2.3.3_andrea2 (should apply quite cleanly
also against clean 2.3.3 or 2.2.9):

Index: linux/arch/i386/lib/usercopy.c
===================================================================
RCS file: /var/cvs/linux/arch/i386/lib/usercopy.c,v
retrieving revision 1.1.2.1
diff -u -r1.1.2.1 usercopy.c
--- linux/arch/i386/lib/usercopy.c 1999/01/18 01:37:02 1.1.2.1
+++ linux/arch/i386/lib/usercopy.c 1999/05/20 13:02:46
@@ -31,6 +31,7 @@
#define __do_strncpy_from_user(dst,src,count,res) \
do { \
int __d0, __d1, __d2; \
+ release_kernel_lock(current); \
__asm__ __volatile__( \
" testl %1,%1\n" \
" jz 2f\n" \
@@ -54,6 +55,7 @@
"=&D" (__d2) \
: "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
: "memory"); \
+ reacquire_kernel_lock(current); \
} while (0)

long
Index: linux/include/asm-i386/smplock.h
===================================================================
RCS file: /var/cvs/linux/include/asm-i386/smplock.h,v
retrieving revision 1.1.2.3
diff -u -r1.1.2.3 smplock.h
--- linux/include/asm-i386/smplock.h 1999/05/01 01:47:32 1.1.2.3
+++ linux/include/asm-i386/smplock.h 1999/05/20 12:47:05
@@ -3,6 +3,10 @@
*
* i386 SMP lock implementation
*/
+
+#ifndef __i386_SMPLOCK_H
+#define __i386_SMPLOCK_H
+
#include <linux/interrupt.h>
#include <asm/spinlock.h>

@@ -11,10 +15,14 @@
/*
* Release global kernel lock and global interrupt lock
*/
-#define release_kernel_lock(task, cpu) \
+#define release_kernel_lock(task) \
do { \
if (task->lock_depth >= 0) \
spin_unlock(&kernel_flag); \
+} while (0)
+#define release_kernel_and_irq_lock(task, cpu) \
+do { \
+ release_kernel_lock(task); \
release_irqlock(cpu); \
__sti(); \
} while (0)
@@ -57,3 +65,5 @@
:"=m" (__dummy_lock(&kernel_flag)),
"=m" (current->lock_depth));
}
+
+#endif /* __i386_SMPLOCK_H */
Index: linux/include/asm-i386/uaccess.h
===================================================================
RCS file: /var/cvs/linux/include/asm-i386/uaccess.h,v
retrieving revision 1.1.2.1
diff -u -r1.1.2.1 uaccess.h
--- linux/include/asm-i386/uaccess.h 1999/01/18 01:33:31 1.1.2.1
+++ linux/include/asm-i386/uaccess.h 1999/05/20 13:01:49
@@ -7,6 +7,7 @@
#include <linux/config.h>
#include <linux/sched.h>
#include <asm/page.h>
+#include <asm/smplock.h>

#define VERIFY_READ 0
#define VERIFY_WRITE 1
@@ -253,6 +254,7 @@
#define __copy_user(to,from,size) \
do { \
int __d0, __d1; \
+ release_kernel_lock(current); \
__asm__ __volatile__( \
"0: rep; movsl\n" \
" movl %3,%0\n" \
@@ -270,11 +272,13 @@
: "=&c"(size), "=&D" (__d0), "=&S" (__d1) \
: "r"(size & 3), "0"(size / 4), "1"(to), "2"(from) \
: "memory"); \
+ reacquire_kernel_lock(current); \
} while (0)

#define __copy_user_zeroing(to,from,size) \
do { \
int __d0, __d1; \
+ release_kernel_lock(current); \
__asm__ __volatile__( \
"0: rep; movsl\n" \
" movl %3,%0\n" \
@@ -298,6 +302,7 @@
: "=&c"(size), "=&D" (__d0), "=&S" (__d1) \
: "r"(size & 3), "0"(size / 4), "1"(to), "2"(from) \
: "memory"); \
+ reacquire_kernel_lock(current); \
} while (0)

/* We let the __ versions of copy_from/to_user inline, because they're often
@@ -324,6 +329,7 @@
int __d0, __d1; \
switch (size & 3) { \
default: \
+ release_kernel_lock(current); \
__asm__ __volatile__( \
"0: rep; movsl\n" \
"1:\n" \
@@ -338,6 +344,7 @@
: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
: "1"(from), "2"(to), "0"(size/4) \
: "memory"); \
+ reacquire_kernel_lock(current); \
break; \
case 1: \
__asm__ __volatile__( \
@@ -408,6 +415,7 @@
int __d0, __d1; \
switch (size & 3) { \
default: \
+ release_kernel_lock(current); \
__asm__ __volatile__( \
"0: rep; movsl\n" \
"1:\n" \
@@ -428,6 +436,7 @@
: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
: "1"(from), "2"(to), "0"(size/4) \
: "memory"); \
+ reacquire_kernel_lock(current); \
break; \
case 1: \
__asm__ __volatile__( \
Index: linux/include/net/checksum.h
===================================================================
RCS file: /var/cvs/linux/include/net/checksum.h,v
retrieving revision 1.1.2.1
diff -u -r1.1.2.1 checksum.h
--- linux/include/net/checksum.h 1999/01/18 01:34:03 1.1.2.1
+++ linux/include/net/checksum.h 1999/05/20 13:07:26
@@ -98,7 +98,13 @@
int len, int sum, int *err_ptr)
{
if (verify_area(VERIFY_READ, src, len) == 0)
- return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
+ {
+ int ret;
+ release_kernel_lock(current);
+ ret = csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
+ reacquire_kernel_lock(current);
+ return ret;
+ }

if (len)
*err_ptr = -EFAULT;
Index: linux/kernel/sched.c
===================================================================
RCS file: /var/cvs/linux/kernel/sched.c,v
retrieving revision 1.1.2.45
diff -u -r1.1.2.45 sched.c
--- linux/kernel/sched.c 1999/05/19 23:43:44 1.1.2.45
+++ linux/kernel/sched.c 1999/05/20 01:38:56
@@ -659,7 +659,7 @@
if (in_interrupt())
goto scheduling_in_interrupt;

- release_kernel_lock(prev, this_cpu);
+ release_kernel_and_irq_lock(prev, this_cpu);

/* Do "administrative" work here while we don't hold any locks */
if (get_active_bhs())

But I just had an Oops with the above patch applyed :-(. But I don't think
the patch is wrong, I think instead there has to be some buggy piece of
code that is triggered by really allowing other piece of locked-codes to
run in the middle of a copy_from/to_user. I'll try to find the real cause
of the Oops now.

BTW, the SMP-lock profiler is just included in my patches (the /proc part
is merged from Andi), so to know how much time the CPU are wasting due
kenrel locks just enable it via the kernel configuration and then cat
/proc/stat:

andrea@laser:/usr/src$ cat /proc/stat
cpu 86196 0 11855 1866185
cpu0 43579 0 5803 932736 486
^^^
cpu1 42617 0 6052 933449 875
^^^
My two cpu wasted (486+875)/HZ sec in spinning over kernel locks since
boot.

Andrea Arcangeli


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:51    [W:0.111 / U:0.356 seconds]
©2003-2011 Jasper Spaans. Advertise on this site