FWIW... IMO it's better to enable access to the relevant compiler intrinsic with platform specific macros, rather than implementing instructions such as Intel's BSWAP or MOVBE by hand. In HPS, isolating endianness concerns from the large integer arithmetic primitives with such macros enabled 25-40% faster performance on big endian platforms. Just as importantly, the intrinsic approach takes significantly less code to implement.
On 8/31/15 10:25 , Eliot Miranda wrote:
Hi Chrises,
my vote would be to write these as 12 numbered primitives, (2,4 & 8
bytes) * (at: & at:put:) * (big & little endian) because they can be performance critical and implementing them like this means the maximum efficiency in both 32-bit and 64-bit Spur, plus the possibility of the JIT implementing the primitives.
On Sun, Aug 30, 2015 at 10:01 PM, Chris Cunningham <cunningham.cb@gmail.com mailto:cunningham.cb@gmail.com> wrote:
Hi Chris, I'm all for having the fastest that in the image that works. If you could make your version handle endianess, then I'm all for including it (at least in the 3 variants that are faster). My first use for this (interface for KAFKA) apparently requires bigEndianess, so I really want that supported. It might be best to keep my naming, though - it follows the name pattern that is already in the class. Or will yours also support 128? -cbc On Sun, Aug 30, 2015 at 2:38 PM, Chris Muller <asqueaker@gmail.com <mailto:asqueaker@gmail.com>> wrote: Hi Chris, I think these methods belong in the image with the fastest implementation we can do. I implemented 64-bit unsigned access for Ma Serializer back in 2005. I modeled my implementation after Andreas' original approach which tries to avoid LI arithmetic. I was curious whether your implementations would be faster, because if they are then it could benefit Magma. After loading "Ma Serializer" 1.5 (or head) into a trunk image, I used the following script to take comparison measurements: | smallN largeN maBa cbBa | smallN := ((2 raisedTo: 13) to: (2 raisedTo: 14)) atRandom. largeN := ((2 raisedTo: 63) to: (2 raisedTo: 64)) atRandom. maBa := ByteArray new: 8. cbBa := ByteArray new: 8. maBa maUint: 64 at: 0 put: largeN. cbBa unsignedLong64At: 1 put: largeN bigEndian: false. self assert: (cbBa maUnsigned64At: 1) = (maBa unsignedLong64At: 1 bigEndian: false). { 'cbc smallN write' -> [ cbBa unsignedLong64At: 1 put: smallN bigEndian: false] bench. 'ma smallN write' -> [cbBa maUint: 64 at: 0 put: smallN ] bench. 'cbc smallN access' -> [ cbBa unsignedLong64At: 1 bigEndian: false. ] bench. 'ma smallN access' -> [ cbBa maUnsigned64At: 1] bench. 'cbc largeN write' -> [ cbBa unsignedLong64At: 1 put: largeN bigEndian: false] bench. 'ma largeN write' -> [cbBa maUint: 64 at: 0 put: largeN ] bench. 'cbc largeN access' -> [ cbBa unsignedLong64At: 1 bigEndian: false ] bench. 'ma largeN access' -> [ cbBa maUnsigned64At: 1] bench. } Here are the results: 'cbc smallN write'->'3,110,000 per second. 322 nanoseconds per run.' . 'ma smallN write'->'4,770,000 per second. 210 nanoseconds per run.' . 'cbc smallN access'->'4,300,000 per second. 233 nanoseconds per run.' . 'ma smallN access'->'16,400,000 per second. 60.9 nanoseconds per run.' . 'cbc largeN write'->'907,000 per second. 1.1 microseconds per run.' . 'ma largeN write'->'6,620,000 per second. 151 nanoseconds per run.' . 'cbc largeN access'->'1,900,000 per second. 527 nanoseconds per run.' . 'ma largeN access'->'1,020,000 per second. 982 nanoseconds per run.' It looks like your 64-bit access is 86% faster for accessing the high-end of the 64-bit range, but slower in the other 3 metrics. Noticeably, it was only 14% as fast for writing the high-end of the 64-bit range, and similarly as much slower for small-number access.. On Fri, Aug 28, 2015 at 6:01 PM, Chris Cunningham <cunningham.cb@gmail.com <mailto:cunningham.cb@gmail.com>> wrote: > Hi. > > I've committed a change to the inbox with changes to allow getting/putting > 64bit values to ByteArrays (similar to 32 and 16 bit accessors). Could this > be added to trunk? > > Also, first time I used the selective commit function - very nice! the > changes I didn't want committed didn't, in fact, get commited. Just the > desirable bits! > > -cbc > > >
-- _,,,^..^,,,_ best, Eliot