Linus Torvalds wrote:
> Don't worry about pa-risc. There may be a handful of users, where even
> "users" is more of a "boot up occasionally just for perverse fun"
> rather than anything else.
Yes, I'm quite aware that, like alpha and ia64, it's purely of historical
interest. It's not even in the
On Wed, Jun 1, 2016 at 7:31 PM, George Spelvin
wrote:
>
> I could use two more iterations of HASH_MIX() or something similar,
> then just take the x value, but that's 6 cycles. If a multiply is
> 4 or 5 cycles, that's a net loss.
Yes. Especially since the multiply will often end up more able to
Linus Torvalds wrote:
> On Mon, May 30, 2016 at 11:10 AM, George Spelvin wrote:
>>
>> I understand, but 64x64-bit multiply on 32-bit is pretty annoyingly
>> expensive. In time, code size, and register pressure which bloats
>> surrounding code.
> Side note, the code seems to work fairly well, but
On Mon, May 30, 2016 at 11:10 AM, George Spelvin
wrote:
>
> I understand, but 64x64-bit multiply on 32-bit is pretty annoyingly
> expensive. In time, code size, and register pressure which bloats
> surrounding code.
Side note, the code seems to work fairly well, but I do worry a bit
about the th
On Mon, 30 May 2016 at 18:27:21 +0200, Peter Zijlstra wrote:
> On Mon, May 30, 2016 at 12:06:18PM -0400, George Spelvin wrote:
> Right; as stated performance really isn't a goal here.
I understand, but 64x64-bit multiply on 32-bit is pretty annoyingly
expensive. In time, code size, and register p
On Mon, May 30, 2016 at 12:06:18PM -0400, George Spelvin wrote:
> Not quite. The fold_hash() you quote is used only on 64-bit systems,
> which can be assumed to have a reasonable 64-bit multiply. On 32-bit
> platforms, I avoid using GOLDEN_RATIO_64 at all, since 64x64-bit
> multiplies are so expe
Peter Zijlstra wrote:
> On Sat, May 28, 2016 at 03:57:19PM -0400, George Spelvin wrote:
>> +static inline unsigned int fold_hash(unsigned long x, unsigned long y)
>> {
>> +y ^= x * GOLDEN_RATIO_64;
>> +y *= GOLDEN_RATIO_64;
>> +return y >> 32;
>> }
> So does it make sense to use tha
On Sat, May 28, 2016 at 03:57:19PM -0400, George Spelvin wrote:
> +static inline unsigned int fold_hash(unsigned long x, unsigned long y)
> {
> + y ^= x * GOLDEN_RATIO_64;
> + y *= GOLDEN_RATIO_64;
> + return y >> 32;
> }
So does it make sense to use that pattern here too?
This cod
8 matches
Mail list logo
