as part of my netmap investigations, i was looking at how
expensive are memory copies, and here are a couple of findings
(first one is obvious, the second one less so)
1. especially on 64bit machines, always use multiple of at
least 8 bytes (possibly even larger units). The bcopy code
in amd
Luigi Rizzo ha scritto:
For small blocks and multiples of 32-64 bytes, i noticed that
the following is a lot faster (breaking even at about 1 KBytes)
static inline void
fast_bcopy(void *_src, void *_dst, int l)
{
uint64_t *src = _src;
Luigi Rizzo wrote:
> 2. apparently, bcopy is not the fastest way to copy memory.
http://now.cs.berkeley.edu/Td/bcopy.html
Best Regards.
Steven.
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It's highly chipset and processor dependent what works best. Intel now
has non-temporal loads and stores which work much better in some cases
but provide little benefit in others.
-Kip
On Wed, May 2, 2012 at 11:52 PM, Steven Atreju wrote:
> Luigi Rizzo wrote:
>> 2. apparently, bcopy is not the f
Hi,
On Wed, May 2, 2012 at 5:52 PM, Steven Atreju wrote:
> Luigi Rizzo wrote:
>> 2. apparently, bcopy is not the fastest way to copy memory.
>
> http://now.cs.berkeley.edu/Td/bcopy.html
>
"Pentium 166, Triton Chipset, EDO memory"... ahem.
- Arnaud
> Best Regards.
>
> Steven.
>
K. Macy wrote [2012-05-03 02:58+0200]:
> It's highly chipset and processor dependent what works best.
Yes, of course.
Though i was kinda, even shocked, once i've seen this first:
http://marc.info/?l=dragonfly-commits&m=132241713812022&w=2
So we don't use our assembler version for new gccs and
2012/5/3, Steven Atreju :
> K. Macy wrote [2012-05-03 02:58+0200]:
>> It's highly chipset and processor dependent what works best.
>
> Yes, of course.
> Though i was kinda, even shocked, once i've seen this first:
>
> http://marc.info/?l=dragonfly-commits&m=132241713812022&w=2
>
> So we don't use
Em 03-05-2012 12:28, Steven Atreju escreveu:
Yes, of course.
Though i was kinda, even shocked, once i've seen this first:
http://marc.info/?l=dragonfly-commits&m=132241713812022&w=2
I also experimented a bit with some trivial libc functions when testing
a change for memcpy (still in queue, w
> > guess this is a good time to thank the FreeBSD hackers for that FPU
> > stack FILD/FISTP idea!
> > I'll append the copy related notes of our doc/memperf.txt.
> > Thanks,
>
> I made an implementation of fpu unwinding and mmx copy to see if they
> were really making a difference years ago (reimp
On Wed, May 02, 2012 at 08:25:57PM +0200, Luigi Rizzo wrote:
> as part of my netmap investigations, i was looking at how
> expensive are memory copies, and here are a couple of findings
> (first one is obvious, the second one less so)
Most C compilers (well, the ones I regularly use) inline small,
On Fri, May 04, 2012 at 09:44:15AM +1000, Andrew Reilly wrote:
> On Wed, May 02, 2012 at 08:25:57PM +0200, Luigi Rizzo wrote:
> > as part of my netmap investigations, i was looking at how
> > expensive are memory copies, and here are a couple of findings
> > (first one is obvious, the second one le
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