Re: [RFC] [PATCH] cache pollution aware __copy_from_user_ll()

Hiro Yoshioka
2005-08-24T14:16:41Z

Hi,

The following patch does not use MMX regsiters so that we don't have
to worry about save/restore the FPU/MMX states.

What do you think?

Some performance data are

Total of GLOBAL_POWER_EVENTS (CPU cycle samples)

2.6.12.4.orig 1921587
2.6.12.4.nt 1688900
1688900/1921587=87.89% (12.1% reduction)

BSQ_CACHE_REFERENCE (L3 cache miss)
2.6.12.4.orig 57427
2.6.12.4.preempt 17122
17122/57427=29.81% (70.18% reduction)

L3 cache miss reduction of __copy_from_user_ll
samples %
37408 65.1412 vmlinux __copy_from_user_ll
24 0.1402 vmlinux __copy_user_zeroing_intel_nocache
24/37408=0.064% (99.93% reduction)

> Top 5 2.6.12.4.orig
> Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 100000
> samples % app name symbol name
> 287643 14.9692 vmlinux __copy_from_user_ll
> 72660 3.7813 vmlinux journal_add_journal_head
> 65011 3.3832 vmlinux do_get_write_access
> 50618 2.6342 vmlinux journal_put_journal_head
> 48068 2.5015 vmlinux journal_dirty_metadata
> pattern9-0-cpu4-0-08191743/summary.out
>
> Counted BSQ_CACHE_REFERENCE events (cache references seen by the bus unit) with a unit mask of 0x3f (multiple flags) count 3000
> samples % app name symbol name
> 134756 7.9364 vmlinux __copy_from_user_ll
> 57735 3.4003 vmlinux journal_add_journal_head
> 50653 2.9832 vmlinux __find_get_block
> 44522 2.6221 vmlinux journal_put_journal_head
> 38928 2.2927 vmlinux journal_dirty_metadata
> pattern9-0-cpu4-0-08191741/summary.out
>
> Counted BSQ_CACHE_REFERENCE events (cache references seen by the bus unit) with a unit mask of 0x200 (read 3rd level cache miss) count 3000
> samples % app name symbol name
> 37408 65.1412 vmlinux __copy_from_user_ll
> 953 1.6595 vmlinux blk_rq_map_sg
> 886 1.5429 vmlinux sub_preempt_count
> 680 1.1841 vmlinux journal_add_journal_head
> 598 1.0413 vmlinux journal_commit_transaction
> pattern9-0-cpu4-0-08191720/summary.out
>

The following data is an implementation without the MMX registers.
Top 5 2.6.12.4.nt
Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 100000
samples % app name symbol name
137744 8.1560 vmlinux __copy_user_zeroing_intel_nocache
68723 4.0692 vmlinux do_get_write_access
65808 3.8966 vmlinux journal_add_journal_head
50373 2.9826 vmlinux journal_dirty_metadata
49038 2.9036 vmlinux journal_put_journal_head
pattern9-0-cpu4-0-08242225/summary.out

Counted BSQ_CACHE_REFERENCE events (cache references seen by the bus unit) with a unit mask of 0x3f (multiple flags) count 3000
samples % app name symbol name
62165 3.7913 vmlinux __copy_user_zeroing_intel_nocache
57862 3.5289 vmlinux journal_add_journal_head
54230 3.3073 vmlinux __find_get_block
48335 2.9478 vmlinux journal_put_journal_head
35737 2.1795 vmlinux journal_dirty_metadata
pattern9-0-cpu4-0-08242152/summary.out

Counted BSQ_CACHE_REFERENCE events (cache references seen by the bus unit) with a unit mask of 0x200 (read 3rd level cache miss) count 3000
samples % app name symbol name
867 5.0637 vmlinux blk_rq_map_sg
694 4.0533 vmlinux journal_add_journal_head
629 3.6736 vmlinux journal_commit_transaction
624 3.6444 vmlinux radix_tree_delete
525 3.0662 vmlinux release_pages
pattern9-0-cpu4-0-08242147/summary.out

The following is MMX version of cache aware implementation.

> Top 5 2.6.12.4.preempt
> Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 100000
> samples % app name symbol name
> 123531 7.5582 vmlinux __copy_user_zeroing_inatomic_nocache
> 64820 3.9660 vmlinux journal_add_journal_head
> 60460 3.6992 vmlinux do_get_write_access
> 47172 2.8862 vmlinux journal_put_journal_head
> 46753 2.8606 vmlinux journal_dirty_metadata
> pattern9-0-cpu4-0-08190838/summary.out
>
> Counted BSQ_CACHE_REFERENCE events (cache references seen by the bus unit) with a unit mask of 0x3f (multiple flags) count 3000
> samples % app name symbol name
> 126762 6.7993 vmlinux __copy_user_zeroing_inatomic_nocache
> 79803 4.2805 vmlinux journal_add_journal_head
> 70271 3.7692 vmlinux journal_dirty_metadata
> 66146 3.5480 vmlinux __find_get_block
> 58082 3.1154 vmlinux journal_put_journal_head
> pattern9-0-cpu4-0-08190855/summary.out
>
> Counted BSQ_CACHE_REFERENCE events (cache references seen by the bus unit) with a unit mask of 0x200 (read 3rd level cache miss) count 3000
> samples % app name symbol name
> 901 5.1788 vmlinux blk_rq_map_sg
> 675 3.8798 vmlinux journal_commit_transaction
> 637 3.6613 vmlinux radix_tree_delete
> 605 3.4774 vmlinux journal_add_journal_head
> 580 3.3337 vmlinux release_pages
> ...
> 51 0.2931 vmlinux __copy_user_zeroing_inatomic_nocache
> ...
> 1 0.0057 vmlinux __copy_from_user_ll_inatomic_nocache
> pattern9-0-cpu4-0-08190859/summary.out

diff -ur linux-2.6.12.4.orig/Makefile linux-2.6.12.4.nt/Makefile
--- linux-2.6.12.4.orig/Makefile 2005-08-12 14:37:59.000000000 +0900
+++ linux-2.6.12.4.nt/Makefile 2005-08-24 17:23:57.000000000 +0900
@@ -1,7 +1,7 @@
VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 12
-EXTRAVERSION = .4.orig
+EXTRAVERSION = .4.nt
NAME=Woozy Numbat

# *DOCUMENTATION*
diff -ur linux-2.6.12.4.orig/arch/i386/lib/usercopy.c linux-2.6.12.4.nt/arch/i386/lib/usercopy.c
--- linux-2.6.12.4.orig/arch/i386/lib/usercopy.c 2005-08-05 16:04:37.000000000 +0900
+++ linux-2.6.12.4.nt/arch/i386/lib/usercopy.c 2005-08-24 21:38:47.000000000 +0900
@@ -10,6 +10,7 @@
#include <linux/highmem.h>
#include <linux/blkdev.h>
#include <linux/module.h>
+#include <asm/i387.h>
#include <asm/uaccess.h>
#include <asm/mmx.h>

@@ -421,6 +422,106 @@
: "eax", "edx", "memory");
return size;
}
+
+/* Non Temporal Hint version of __copy_user_zeroing_intel */
+/* It is cache aware. */
+/* hyoshiok@miraclelinux.com */
+static unsigned long
+__copy_user_zeroing_intel_nocache(void *to, const void __user *from, unsigned long size)
+{
+ int d0, d1;
+
+ __asm__ __volatile__(
+ " .align 2,0x90\n"
+ "0: movl 32(%4), %%eax\n"
+ " cmpl $67, %0\n"
+ " jbe 2f\n"
+ "1: movl 64(%4), %%eax\n"
+ " .align 2,0x90\n"
+ "2: movl 0(%4), %%eax\n"
+ "21: movl 4(%4), %%edx\n"
+ " movnti %%eax, 0(%3)\n"
+ " movnti %%edx, 4(%3)\n"
+ "3: movl 8(%4), %%eax\n"
+ "31: movl 12(%4),%%edx\n"
+ " movnti %%eax, 8(%3)\n"
+ " movnti %%edx, 12(%3)\n"
+ "4: movl 16(%4), %%eax\n"
+ "41: movl 20(%4), %%edx\n"
+ " movnti %%eax, 16(%3)\n"
+ " movnti %%edx, 20(%3)\n"
+ "10: movl 24(%4), %%eax\n"
+ "51: movl 28(%4), %%edx\n"
+ " movnti %%eax, 24(%3)\n"
+ " movnti %%edx, 28(%3)\n"
+ "11: movl 32(%4), %%eax\n"
+ "61: movl 36(%4), %%edx\n"
+ " movnti %%eax, 32(%3)\n"
+ " movnti %%edx, 36(%3)\n"
+ "12: movl 40(%4), %%eax\n"
+ "71: movl 44(%4), %%edx\n"
+ " movnti %%eax, 40(%3)\n"
+ " movnti %%edx, 44(%3)\n"
+ "13: movl 48(%4), %%eax\n"
+ "81: movl 52(%4), %%edx\n"
+ " movnti %%eax, 48(%3)\n"
+ " movnti %%edx, 52(%3)\n"
+ "14: movl 56(%4), %%eax\n"
+ "91: movl 60(%4), %%edx\n"
+ " movnti %%eax, 56(%3)\n"
+ " movnti %%edx, 60(%3)\n"
+ " addl $-64, %0\n"
+ " addl $64, %4\n"
+ " addl $64, %3\n"
+ " cmpl $63, %0\n"
+ " ja 0b\n"
+ "5: movl %0, %%eax\n"
+ " shrl $2, %0\n"
+ " andl $3, %%eax\n"
+ " cld\n"
+ "6: rep; movsl\n"
+ " movl %%eax,%0\n"
+ "7: rep; movsb\n"
+ "8:\n"
+ ".section .fixup,\"ax\"\n"
+ "9: lea 0(%%eax,%0,4),%0\n"
+ "16: pushl %0\n"
+ " pushl %%eax\n"
+ " xorl %%eax,%%eax\n"
+ " rep; stosb\n"
+ " popl %%eax\n"
+ " popl %0\n"
+ " jmp 8b\n"
+ ".previous\n"
+ ".section __ex_table,\"a\"\n"
+ " .align 4\n"
+ " .long 0b,16b\n"
+ " .long 1b,16b\n"
+ " .long 2b,16b\n"
+ " .long 21b,16b\n"
+ " .long 3b,16b\n"
+ " .long 31b,16b\n"
+ " .long 4b,16b\n"
+ " .long 41b,16b\n"
+ " .long 10b,16b\n"
+ " .long 51b,16b\n"
+ " .long 11b,16b\n"
+ " .long 61b,16b\n"
+ " .long 12b,16b\n"
+ " .long 71b,16b\n"
+ " .long 13b,16b\n"
+ " .long 81b,16b\n"
+ " .long 14b,16b\n"
+ " .long 91b,16b\n"
+ " .long 6b,9b\n"
+ " .long 7b,16b\n"
+ ".previous"
+ : "=&c"(size), "=&D" (d0), "=&S" (d1)
+ : "1"(to), "2"(from), "0"(size)
+ : "eax", "edx", "memory");
+ return size;
+}
+
#else
/*
* Leave these declared but undefined. They should not be any references to
@@ -430,6 +531,8 @@
__copy_user_zeroing_intel(void *to, const void __user *from, unsigned long size);
unsigned long
__copy_user_intel(void __user *to, const void *from, unsigned long size);
+unsigned long
+__copy_user_zeroing_intel_nocache(void *to, const void __user *from, unsigned long size);
#endif /* CONFIG_X86_INTEL_USERCOPY */

/* Generic arbitrary sized copy. */
@@ -511,7 +614,6 @@
: "memory"); \
} while (0)

-
unsigned long __copy_to_user_ll(void __user *to, const void *from, unsigned long n)
{
BUG_ON((long) n < 0);
@@ -582,6 +684,21 @@
return n;
}

+unsigned long
+__copy_from_user_ll_nocache(void *to, const void __user *from, unsigned long n)
+{
+ BUG_ON((long)n < 0);
+#ifdef CONFIG_X86_INTEL_USERCOPY
+ if ( n > 64)
+ n = __copy_user_zeroing_intel_nocache(to, from, n);
+ else
+ __copy_user_zeroing(to, from, n);
+#else
+ __copy_user_zeroing(to, from, n);
+#endif
+ return n;
+}
+
/**
* copy_to_user: - Copy a block of data into user space.
* @to: Destination address, in user space.
diff -ur linux-2.6.12.4.orig/include/asm-i386/uaccess.h linux-2.6.12.4.nt/include/asm-i386/uaccess.h
--- linux-2.6.12.4.orig/include/asm-i386/uaccess.h 2005-08-05 16:04:37.000000000 +0900
+++ linux-2.6.12.4.nt/include/asm-i386/uaccess.h 2005-08-24 18:18:57.000000000 +0900
@@ -413,6 +413,8 @@
const void *from, unsigned long n);
unsigned long __must_check __copy_from_user_ll(void *to,
const void __user *from, unsigned long n);
+unsigned long __must_check __copy_from_user_ll_nocache(void *to,
+ const void __user *from, unsigned long n);

/*
* Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault
@@ -502,11 +504,40 @@
}

static inline unsigned long
+__copy_from_user_inatomic_nocache(void *to, const void __user *from, unsigned long n)
+{
+ if (__builtin_constant_p(n)) {
+ unsigned long ret;
+
+ switch (n) {
+ case 1:
+ __get_user_size(*(u8 *)to, from, 1, ret, 1);
+ return ret;
+ case 2:
+ __get_user_size(*(u16 *)to, from, 2, ret, 2);
+ return ret;
+ case 4:
+ __get_user_size(*(u32 *)to, from, 4, ret, 4);
+ return ret;
+ }
+ }
+ return __copy_from_user_ll_nocache(to, from, n);
+}
+
+static inline unsigned long
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
might_sleep();
return __copy_from_user_inatomic(to, from, n);
}
+
+static inline unsigned long
+__copy_from_user_nocache(void *to, const void __user *from, unsigned long n)
+{
+ might_sleep();
+ return __copy_from_user_inatomic_nocache(to, from, n);
+}
+
unsigned long __must_check copy_to_user(void __user *to,
const void *from, unsigned long n);
unsigned long __must_check copy_from_user(void *to,
diff -ur linux-2.6.12.4.orig/mm/filemap.c linux-2.6.12.4.nt/mm/filemap.c
--- linux-2.6.12.4.orig/mm/filemap.c 2005-08-05 16:04:37.000000000 +0900
+++ linux-2.6.12.4.nt/mm/filemap.c 2005-08-16 10:16:06.000000000 +0900
@@ -1727,13 +1727,13 @@
int left;

kaddr = kmap_atomic(page, KM_USER0);
- left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
+ left = __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes);
kunmap_atomic(kaddr, KM_USER0);

if (left != 0) {
/* Do it the slow way */
kaddr = kmap(page);
- left = __copy_from_user(kaddr + offset, buf, bytes);
+ left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
kunmap(page);
}
return bytes - left;
@@ -1750,7 +1750,7 @@
int copy = min(bytes, iov->iov_len - base);

base = 0;
- left = __copy_from_user_inatomic(vaddr, buf, copy);
+ left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
copied += copy;
bytes -= copy;
vaddr += copy;

Regards,
Hiro
--
Hiro Yoshioka
CTO/Miracle Linux Corporation