Simple Performance Counters: SLUB instrumentation
Subsystems (2)
PATCH 7/7 Simple Performance Counters: SLUB instrumentation
With this patch SLUB will perform tests on bootup and display results.
--- mm/slub.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 files changed, 92 insertions(+), 5 deletions(-)
mm/slub.c +92 -5
@@ -20,6 +20,7 @@#include <linux/mempolicy.h> #include <linux/ctype.h> #include <linux/kallsyms.h> +#include <linux/perf.h> /* * Lock order:
@@ -152,6 +153,7 @@ static inline void ClearSlabDebug(struct page *page)/* Enable to test recovery from slab corruption on boot */ #undef SLUB_RESILIENCY_TEST +#undef SLUB_PERFORMANCE_TEST#if PAGE_SHIFT <=12
@@ -2870,9 +2872,97 @@ static long validate_slab_cache(struct kmem_cache *s)return count; } -#ifdef SLUB_RESILIENCY_TEST static void resiliency_test (void ) { +#ifdef SLUB_PERFORMANCE_TEST +#define TEST_COUNT 10000 +int size, i; +struct pc x; +void **v =kmalloc (TEST_COUNT *sizeof (void *),GFP_KERNEL ); + +printk (KERN_INFO "SLUB Performance testing\n" ); +printk (KERN_INFO "========================\n" ); +printk (KERN_INFO "1. Kmalloc: Repeatedly allocate then free test\n" ); +for (size =8 ; size <=PAGE_SIZE <<2 ; size <<=1 ) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) { + v[i] =kmalloc (size,GFP_KERNEL ); + } +printk (KERN_INFO "%i times kmalloc(%d) = " , i, size); +pc_stop_printk (&x); +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kfree (v[i]); +printk (" kfree() = " ); +pc_stop_printk (&x); +printk ("\n" ); + } + +printk (KERN_INFO "2. Kmalloc: alloc/free test\n" ); +for (size =8 ; size <=PAGE_SIZE <<2 ; size <<=1 ) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kfree (kmalloc (size,GFP_KERNEL )); +printk (KERN_INFO "%i times kmalloc(%d)/kfree = " , i, size); +pc_stop_printk (&x); +printk ("\n" ); + } +printk (KERN_INFO "3. kmem_cache_alloc: Repeatedly allocate then free test\n" ); +for (size =3 ; size <=PAGE_SHIFT ; size ++) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) { + v[i] =kmem_cache_alloc (kmalloc_caches + size,GFP_KERNEL ); + } +printk (KERN_INFO "%d times kmem_cache_alloc(%d) = " , i,1 << size); +pc_stop_printk (&x); +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kmem_cache_free (kmalloc_caches + size, v[i]); +printk (" kmem_cache_free() = " ); +pc_stop_printk (&x); +printk ("\n" ); + } + +printk (KERN_INFO "4. kmem_cache_alloc: alloc/free test\n" ); +for (size =3 ; size <=PAGE_SHIFT ; size++) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kmem_cache_free (kmalloc_caches + size, +kmem_cache_alloc (kmalloc_caches + size, +GFP_KERNEL )); +printk (KERN_INFO "%d times kmem_cache_alloc(%d)/kmem_cache_free = " , i,1 << size); +pc_stop_printk (&x); +printk ("\n" ); + } +printk (KERN_INFO "5. kmem_cache_zalloc: Repeatedly allocate then free test\n" ); +for (size =3 ; size <=PAGE_SHIFT ; size ++) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) { + v[i] =kmem_cache_zalloc (kmalloc_caches + size,GFP_KERNEL ); + } +printk (KERN_INFO "%d times kmem_cache_zalloc(%d) = " , i,1 << size); +pc_stop_printk (&x); +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kmem_cache_free (kmalloc_caches + size, v[i]); +printk (" kmem_cache_free() = " ); +pc_stop_printk (&x); +printk ("\n" ); + } + +printk (KERN_INFO "6. kmem_cache_zalloc: alloc/free test\n" ); +for (size =3 ; size <=PAGE_SHIFT ; size++) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kmem_cache_free (kmalloc_caches + size, +kmem_cache_zalloc (kmalloc_caches + size, +GFP_KERNEL )); +printk (KERN_INFO "%d times kmem_cache_zalloc(%d)/kmem_cache_free = " , i,1 << size); +pc_stop_printk (&x); +printk ("\n" ); + } +#endif +#ifdef SLUB_RESILIENCY_TEST u8 *p;printk (KERN_ERR "SLUB resiliency testing\n" );
@@ -2920,11 +3010,8 @@ static void resiliency_test(void) p[512 ] =0xab ;printk (KERN_ERR "\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n" , p);validate_slab_cache (kmalloc_caches +9 ); -} -#else -static void resiliency_test (void ) {};#endif - +}/* * Generate lists of code addresses where slabcache objects are allocated * and freed.
Signature · 1 line
1.5.2.4
Hi Christoph,
A few remarks on these tests:
Why do you printk inside the timing period ? Filling the printk buffers or outputting on things such as serial console could really hurt your results.
I hope you run your system with idle=poll and without frequency scaling at all, because otherwise your cycle count would be completely off on many AMD and Intel CPUs. You can have a look at this (very rough) document on the topic:
http://ltt.polymtl.ca/ > "Notes on AMD and Intel asynchronous TSC
architectures (with workarounds)"
http://ltt.polymtl.ca/svn/ltt/branches/poly/doc/developer/tsc.txt
I would be tempted to try running these tests with interrupts disabled, just to make sure that the timings are not too much modified by the system load. Especially since you are comparing an algorithm that disables interrupts with one that doesn't, it would be unfair to say that the second one is slower just because less interrupts have been serviced during its execution.
Mathieu
Quoted 148 lines · * Christoph Lameter ([email protected]) wrote:
With this patch SLUB will perform tests on bootup and display results.
Signed-off-by Christoph Lameter <[email protected]>--- mm/slub.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 files changed, 92 insertions(+), 5 deletions(-)mm/slub.c +92
-5@@ -20,6 +20,7 @@#include <linux/mempolicy.h> #include <linux/ctype.h> #include <linux/kallsyms.h> +#include <linux/perf.h> /* * Lock order: @@ -152,6 +153,7 @@ static inline void ClearSlabDebug(struct page *page)/* Enable to test recovery from slab corruption on boot */ #undef SLUB_RESILIENCY_TEST +#undef SLUB_PERFORMANCE_TEST#if PAGE_SHIFT <=12 @@ -2870,9 +2872,97 @@ static long validate_slab_cache(struct kmem_cache *s)return count; } -#ifdef SLUB_RESILIENCY_TEST static void resiliency_test (void ) { +#ifdef SLUB_PERFORMANCE_TEST +#define TEST_COUNT 10000 +int size, i; +struct pc x; +void **v =kmalloc (TEST_COUNT *sizeof (void *),GFP_KERNEL ); + +printk (KERN_INFO "SLUB Performance testing\n" ); +printk (KERN_INFO "========================\n" ); +printk (KERN_INFO "1. Kmalloc: Repeatedly allocate then free test\n" ); +for (size =8 ; size <=PAGE_SIZE <<2 ; size <<=1 ) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) { + v[i] =kmalloc (size,GFP_KERNEL ); + } +printk (KERN_INFO "%i times kmalloc(%d) = " , i, size); +pc_stop_printk (&x); +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kfree (v[i]); +printk (" kfree() = " ); +pc_stop_printk (&x); +printk ("\n" ); + } + +printk (KERN_INFO "2. Kmalloc: alloc/free test\n" ); +for (size =8 ; size <=PAGE_SIZE <<2 ; size <<=1 ) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kfree (kmalloc (size,GFP_KERNEL )); +printk (KERN_INFO "%i times kmalloc(%d)/kfree = " , i, size); +pc_stop_printk (&x); +printk ("\n" ); + } +printk (KERN_INFO "3. kmem_cache_alloc: Repeatedly allocate then free test\n" ); +for (size =3 ; size <=PAGE_SHIFT ; size ++) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) { + v[i] =kmem_cache_alloc (kmalloc_caches + size,GFP_KERNEL ); + } +printk (KERN_INFO "%d times kmem_cache_alloc(%d) = " , i,1 << size); +pc_stop_printk (&x); +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kmem_cache_free (kmalloc_caches + size, v[i]); +printk (" kmem_cache_free() = " ); +pc_stop_printk (&x); +printk ("\n" ); + } + +printk (KERN_INFO "4. kmem_cache_alloc: alloc/free test\n" ); +for (size =3 ; size <=PAGE_SHIFT ; size++) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kmem_cache_free (kmalloc_caches + size, +kmem_cache_alloc (kmalloc_caches + size, +GFP_KERNEL )); +printk (KERN_INFO "%d times kmem_cache_alloc(%d)/kmem_cache_free = " , i,1 << size); +pc_stop_printk (&x); +printk ("\n" ); + } +printk (KERN_INFO "5. kmem_cache_zalloc: Repeatedly allocate then free test\n" ); +for (size =3 ; size <=PAGE_SHIFT ; size ++) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) { + v[i] =kmem_cache_zalloc (kmalloc_caches + size,GFP_KERNEL ); + } +printk (KERN_INFO "%d times kmem_cache_zalloc(%d) = " , i,1 << size); +pc_stop_printk (&x); +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kmem_cache_free (kmalloc_caches + size, v[i]); +printk (" kmem_cache_free() = " ); +pc_stop_printk (&x); +printk ("\n" ); + } + +printk (KERN_INFO "6. kmem_cache_zalloc: alloc/free test\n" ); +for (size =3 ; size <=PAGE_SHIFT ; size++) { +pc_start (&x); +for (i =0 ; i <TEST_COUNT ; i++) +kmem_cache_free (kmalloc_caches + size, +kmem_cache_zalloc (kmalloc_caches + size, +GFP_KERNEL )); +printk (KERN_INFO "%d times kmem_cache_zalloc(%d)/kmem_cache_free = " , i,1 << size); +pc_stop_printk (&x); +printk ("\n" ); + } +#endif +#ifdef SLUB_RESILIENCY_TEST u8 *p;printk (KERN_ERR "SLUB resiliency testing\n" );@@ -2920,11 +3010,8 @@ static void resiliency_test(void) p[512 ] =0xab ;printk (KERN_ERR "\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n" , p);validate_slab_cache (kmalloc_caches +9 ); -} -#else -static void resiliency_test (void ) {};#endif - +}/* * Generate lists of code addresses where slabcache objects are allocated * and freed. Signature · 7 lines
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Signature · 3 lines
Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
Quoted 3 lines · Mathieu Desnoyers
Why do you printk inside the timing period ? Filling the printk buffers or outputting on things such as serial console could really hurt your results.
It was easier to code?
Quoted 4 lines
I hope you run your system with idle=poll and without frequency scaling at all, because otherwise your cycle count would be completely off on many AMD and Intel CPUs. You can have a look at this (very rough) document on the topic:
The cpu will definitely not be idle during these measurements and no frequency scaling is active.
Quoted 8 lines · * Christoph Lameter ([email protected]) wrote:
Quoted 3 lines · Mathieu Desnoyers
Why do you printk inside the timing period ? Filling the printk buffers or outputting on things such as serial console could really hurt your results.
It was easier to code?
Quoted 7 lines
Quoted 4 lines
I hope you run your system with idle=poll and without frequency scaling at all, because otherwise your cycle count would be completely off on many AMD and Intel CPUs. You can have a look at this (very rough) document on the topic:
The cpu will definitely not be idle during these measurements and no frequency scaling is active.
The problem is that if the cpu is idle _before_ the measurements, the frequency will change differently from one cpu to another. Therefore, the cycle counters may have large offsets when you start your tests. So, if get_cycles() is executed on different CPUs (thread being migrated) between the beginning and the end of the test, the results would be skewed.
Mathieu
Signature · 3 lines
Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
Quoted 9 lines · Mathieu Desnoyers
Quoted 2 lines
The cpu will definitely not be idle during these measurements and no frequency scaling is active.
The problem is that if the cpu is idle _before_ the measurements, the frequency will change differently from one cpu to another. Therefore, the cycle counters may have large offsets when you start your tests. So, if
get_cycles()is executed on different CPUs (thread being migrated) between the beginning and the end of the test, the results would be skewed.
TSC measurements as done by this patch are associated with cpus. The skew is irrelevant. Development of this patchset was done on a system whose TSC are never synchronized.