On x86, I tested a Sandy Bridge with AVX with 12M cache and a Haswell with AVX+FMA with 6M cache on MatrixXf sizes up to 2400.
I could not see any significant impact of this offset.
On Nexus 5, the offset has a slight effect: values around 32 (times sizeof float) are worst. Anything else is the same: the current 64 (8*pk), or... 0.
So let's just go with 0!
Note that we needed a fix anyway for not accounting for the value of RhsProgress. 0 nicely avoids the issue altogether!
- the first prefetch is actually harmful on Haswell with FMA,
but it is the most beneficial on ARM.
- the second prefetch... I was very stupid and multiplied by sizeof(scalar)
and offset of a scalar* pointer. The old offset was 64; pk = 8, so 64=pk*8.
So this effectively restores the older offset. Actually, there were
two prefetches here, one with offset 48 and one with offset 64. I could not
confirm any benefit from this strange 48 offset on either the haswell or
my ARM device.
This is substantially faster on ARM, where it's important to minimize the number of loads.
This is specific to the case where all packet types are of size 4. I made my best attempt to minimize how dirty this is... opinions welcome.
Eventually one could have a generic rotated kernel, but it would take some work to get there. Also, on sandy bridge, in my experience, it's not beneficial (even about 1% slower).
This is only a debugging/testing patch. It allows testing specific
product blocking sizes, typically to study the impact on performance.
Example usage:
int testk, testm, testn;
#define EIGEN_TEST_SPECIFIC_BLOCKING_SIZES
#define EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_K testk
#define EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_M testm
#define EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_N testn
#include <Eigen/Core>
bug #877, bug #572: Get rid of Index conversion warnings, summary of changes:
- Introduce a global typedef Eigen::Index making Eigen::DenseIndex and AnyExpr<>::Index deprecated (default is std::ptrdiff_t).
- Eigen::Index is used throughout the API to represent indices, offsets, and sizes.
- Classes storing an array of indices uses the type StorageIndex to store them. This is a template parameter of the class. Default is int.
- Methods that *explicitly* set or return an element of such an array take or return a StorageIndex type. In all other cases, the Index type is used.
- fix usage of Index (API) versus StorageIndex (when multiple indexes are stored)
- use StorageIndex(val) when the input has already been check
- use internal::convert_index<StorageIndex>(val) when val is potentially unsafe (directly comes from user input)
