[Intel-gfx] [RFC PATCH 1/1] drm/mm: add ig_frag selftest
Christian König
christian.koenig at amd.com
Tue Jun 2 14:25:02 UTC 2020
Am 02.06.20 um 16:13 schrieb Nirmoy:
> Hi Christian,
>
> On 6/2/20 2:47 PM, Christian König wrote:
>> Nirmoy please keep in mind that your current implementation doesn't
>> fully solve the issue the test case is exercising.
>>
>> In other words what you have implement is fast skipping of fragmented
>> address space for bottom-up and top-down.
>>
>> But what this test here exercises is the fast skipping of aligned
>> allocations. You should probably adjust the test case a bit.
>
>
> Allocations with size=4k and aign = 8k is known to introduce
> fragmentation,
Yes, but this fragmentation can't be avoided with what we already
implemented. For this we would need the extension with the alignment I
already explained.
> do you mean I should only test bottom-up and top-down
>
> for now ?
Yes and no.
What we need to test is the following:
1. Make tons of allocations with size=4k and align=0.
2. Free every other of those allocations.
3. Make tons of allocations with size=8k and align=0.
Previously bottom-up and top-down would have checked all the holes
created in step #2.
With your change they can immediately see that this doesn't make sense
and shortcut to the leftmost/rightmost leaf node in the tree with the
large free block.
That we can handle the alignment as well is the next step of that.
Regards,
Christian.
>
>
> Regards,
>
> Nirmoy
>
>
>>
>>
>> Regards,
>> Christian.
>>
>> Am 29.05.20 um 23:01 schrieb Nirmoy:
>>>
>>> On 5/29/20 5:52 PM, Chris Wilson wrote:
>>>> Quoting Nirmoy (2020-05-29 16:40:53)
>>>>> This works correctly most of the times but sometimes
>>>
>>>
>>> I have to take my word back. In another machine, 20k insertions in
>>>
>>> best mode takes 6-9 times more than 10k insertions, all most all the
>>> time.
>>>
>>> evict, bottom-up and top-down modes remains in 2-5 times range.
>>>
>>>
>>> If I reduce the insertions to 1k and 2k then scaling factor for best
>>> mode stays below 4 most of the time.
>>>
>>> evict, bottom-up and top-down modes remains in 2-3 times range.
>>>
>>>
>>> I wonder if it makes sense to test with only 1k and 2k insertions
>>> and tolerate more than error if the mode == best.
>>>
>>> Regards,
>>>
>>> Nirmoy
>>>
>>>>>
>>>>> 20k insertions can take more than 8 times of 10k insertion time.
>>>> The pressure is on to improve then :)
>>>>
>>>>> Regards,
>>>>>
>>>>> Nirmoy
>>>>>
>>>>> On 5/29/20 6:33 PM, Nirmoy Das wrote:
>>>>>> This patch introduces fragmentation in the address range
>>>>>> and measures time taken by 10k and 20k insertions. ig_frag()
>>>>>> will fail if time taken by 20k insertions takes more than 4 times
>>>>>> of 10k insertions as we know that insertions scale quadratically.
>>>>>> Also tolerate 10% error because of kernel scheduler's jitters.
>>>>>>
>>>>>> Output:
>>>>>> <snip>
>>>>>> [ 8092.653518] drm_mm: Testing DRM range manger (struct drm_mm),
>>>>>> with random_seed=0x9bfb4117 max_iterations=8192 max_prime=128
>>>>>> [ 8092.653520] drm_mm: igt_sanitycheck - ok!
>>>>>> [ 8092.653525] igt_debug 0x0000000000000000-0x0000000000000200:
>>>>>> 512: free
>>>>>> [ 8092.653526] igt_debug 0x0000000000000200-0x0000000000000600:
>>>>>> 1024: used
>>>>>> [ 8092.653527] igt_debug 0x0000000000000600-0x0000000000000a00:
>>>>>> 1024: free
>>>>>> [ 8092.653528] igt_debug 0x0000000000000a00-0x0000000000000e00:
>>>>>> 1024: used
>>>>>> [ 8092.653529] igt_debug 0x0000000000000e00-0x0000000000001000:
>>>>>> 512: free
>>>>>> [ 8092.653529] igt_debug total: 4096, used 2048 free 2048
>>>>>> [ 8112.569813] drm_mm: best fragmented insert of 10000 and 20000
>>>>>> insertions took 504 and 1996 msecs
>>>>>> [ 8112.723254] drm_mm: bottom-up fragmented insert of 10000 and
>>>>>> 20000 insertions took 44 and 108 msecs
>>>>>> [ 8112.813212] drm_mm: top-down fragmented insert of 10000 and
>>>>>> 20000 insertions took 40 and 44 msecs
>>>>>> [ 8112.847733] drm_mm: evict fragmented insert of 10000 and 20000
>>>>>> insertions took 8 and 20 msecs
>>>>>> <snip>
>>>>>>
>>>>>> Signed-off-by: Nirmoy Das <nirmoy.das at amd.com>
>>>>>> ---
>>>>>> drivers/gpu/drm/selftests/drm_mm_selftests.h | 1 +
>>>>>> drivers/gpu/drm/selftests/test-drm_mm.c | 73
>>>>>> ++++++++++++++++++++
>>>>>> 2 files changed, 74 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/selftests/drm_mm_selftests.h
>>>>>> b/drivers/gpu/drm/selftests/drm_mm_selftests.h
>>>>>> index 6b943ea1c57d..8c87c964176b 100644
>>>>>> --- a/drivers/gpu/drm/selftests/drm_mm_selftests.h
>>>>>> +++ b/drivers/gpu/drm/selftests/drm_mm_selftests.h
>>>>>> @@ -14,6 +14,7 @@ selftest(insert, igt_insert)
>>>>>> selftest(replace, igt_replace)
>>>>>> selftest(insert_range, igt_insert_range)
>>>>>> selftest(align, igt_align)
>>>>>> +selftest(frag, igt_frag)
>>>>>> selftest(align32, igt_align32)
>>>>>> selftest(align64, igt_align64)
>>>>>> selftest(evict, igt_evict)
>>>>>> diff --git a/drivers/gpu/drm/selftests/test-drm_mm.c
>>>>>> b/drivers/gpu/drm/selftests/test-drm_mm.c
>>>>>> index 9aabe82dcd3a..05d8f3659b4d 100644
>>>>>> --- a/drivers/gpu/drm/selftests/test-drm_mm.c
>>>>>> +++ b/drivers/gpu/drm/selftests/test-drm_mm.c
>>>>>> @@ -1033,6 +1033,79 @@ static int igt_insert_range(void *ignored)
>>>>>> return 0;
>>>>>> }
>>>>>> +static int get_insert_time(unsigned int num_insert,
>>>>>> + const struct insert_mode *mode)
>>>>>> +{
>>>>>> + struct drm_mm mm;
>>>>>> + struct drm_mm_node *nodes, *node, *next;
>>>>>> + unsigned int size = 4096, align = 8192;
>>>>>> + unsigned long start;
>>>>>> + unsigned int i;
>>>>>> + int ret = -EINVAL;
>>>>>> +
>>>>>> + drm_mm_init(&mm, 1, U64_MAX - 2);
>>>>>> + nodes = vzalloc(array_size(num_insert, sizeof(*nodes)));
>>>>>> + if (!nodes)
>>>>>> + goto err;
>>>>>> +
>>>>>> + start = jiffies;
>>>> Use ktime_t start = ktime_now();
>>>>
>>>>>> + for (i = 0; i < num_insert; i++) {
>>>>>> + if (!expect_insert(&mm, &nodes[i], size, align, i,
>>>>>> mode)) {
>>>>>> + pr_err("%s insert failed\n", mode->name);
>>>>>> + goto out;
>>>>>> + }
>>>>>> + }
>>>>>> +
>>>>>> + ret = jiffies_to_msecs(jiffies - start);
>>>> ret = ktime_sub(ktime_now(), start);
>>>>
>>>> The downside to using ktime is remembering it is s64 and so
>>>> requires care
>>>> and attention in doing math.
>>>>
>>>>>> +out:
>>>>>> + drm_mm_for_each_node_safe(node, next, &mm)
>>>>>> + drm_mm_remove_node(node);
>>>>>> + drm_mm_takedown(&mm);
>>>>>> + vfree(nodes);
>>>>>> +err:
>>>>>> + return ret;
>>>>>> +
>>>>>> +}
>>>>>> +
>>>>>> +static int igt_frag(void *ignored)
>>>>>> +{
>>>>>> + const struct insert_mode *mode;
>>>>>> + unsigned int insert_time1, insert_time2;
>>>>>> + unsigned int insert_size = 10000;
>>>>>> + unsigned int scale_factor = 4;
>>>>>> + /* tolerate 10% excess insertion duration */
>>>>>> + unsigned int error_factor = 110;
>>>>>> + int ret = -EINVAL;
>>>>>> +
>>>>>> + for (mode = insert_modes; mode->name; mode++) {
>>>>>> + unsigned int expected_time;
>>>>>> +
>>>>>> + insert_time1 = get_insert_time(insert_size, mode);
>>>>>> + if (insert_time1 < 0)
>>>>>> + goto err;
>>>> Ah, can you propagate the actual error. I see you are returning EINVAL
>>>> for ENOMEM errors. Just wait until it hits and you have to debug
>>>> why :)
>>>>
>>>>>> + insert_time2 = get_insert_time((insert_size * 2),
>>>>>> mode);
>>>>>> + if (insert_time2 < 0)
>>>>>> + goto err;
>>>>>> +
>>>>>> + expected_time = (scale_factor * insert_time1 *
>>>>>> + error_factor)/100;
>>>>>> + if (insert_time2 > expected_time) {
>>>>>> + pr_err("%s fragmented insert took more %u
>>>>>> msecs\n",
>>>>>> + mode->name, insert_time2 -
>>>>>> expected_time);
>>>>>> + goto err;
>>>>>> + }
>>>>>> +
>>>>>> + pr_info("%s fragmented insert of %u and %u
>>>>>> insertions took %u and %u msecs\n",
>>>>>> + mode->name, insert_size, insert_size * 2,
>>>>>> insert_time1,
>>>>>> + insert_time2);
>>>> Put the info first before the error. We always want the full details,
>>>> with the error message explaining why it's unhappy.
>>>> -Chris
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>>>>
>>
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