On Tue, Jan 18, 2022, at 21:55, Warren Weckesser wrote:
> expr = 'z.real**2 + z.imag**2'
>
> z = generate_sample(n, rng)
🤔 If I duplicate the `z = ...` line, I get the fast result throughout. If,
however, I use `generate_sample(1, rng)` (or any other value than `n`), it does
not improve matters
Might be a 'warmup' of the timeit module?
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On Wed, Jan 19, 2022 at 7:33 AM Stefan van der Walt
wrote:
> On Tue, Jan 18, 2022, at 21:55, Warren Weckesser wrote:
> > expr = 'z.real**2 + z.imag**2'
> >
> > z = generate_sample(n, rng)
>
> 🤔 If I duplicate the `z = ...` line, I get the fast result throughout.
> If, however, I use `generate_sam
On Wed, Jan 19, 2022 at 11:50 AM Francesc Alted wrote:
>
>
> On Wed, Jan 19, 2022 at 7:33 AM Stefan van der Walt
> wrote:
>
>> On Tue, Jan 18, 2022, at 21:55, Warren Weckesser wrote:
>> > expr = 'z.real**2 + z.imag**2'
>> >
>> > z = generate_sample(n, rng)
>>
>> 🤔 If I duplicate the `z = ...` li
On Wed, 2022-01-19 at 11:49 +0100, Francesc Alted wrote:
> On Wed, Jan 19, 2022 at 7:33 AM Stefan van der Walt
>
> wrote:
>
> > On Tue, Jan 18, 2022, at 21:55, Warren Weckesser wrote:
> > > expr = 'z.real**2 + z.imag**2'
> > >
> > > z = generate_sample(n, rng)
> >
> > 🤔 If I duplicate the `z =
On Wed, Jan 19, 2022 at 6:58 PM Stanley Seibert
wrote:
> Given that this seems to be Linux only, is this related to how glibc does
> large allocations (>128kB) using mmap()?
>
> https://stackoverflow.com/a/33131385
>
That's a good point. As MMAP_THRESHOLD is 128 KB, and the size of `z` is
almost
On Wed, 19 Jan 2022 19:48:32 +0100
Francesc Alted wrote:
> What puzzles me is that the timeit loops access `z` data 3*1
> times, which is plenty of time for doing the allocation (just should
> require just a single iteration).
Hi all,
Very interesting discussion ... IIRC, timeit does some c
On Wed, 2022-01-19 at 19:48 +0100, Francesc Alted wrote:
> On Wed, Jan 19, 2022 at 6:58 PM Stanley Seibert
>
> wrote:
>
> > Given that this seems to be Linux only, is this related to how
> > glibc does
> > large allocations (>128kB) using mmap()?
> >
> > https://stackoverflow.com/a/33131385
> >
On Wed, 2022-01-19 at 20:49 +0100, Jerome Kieffer wrote:
> On Wed, 19 Jan 2022 19:48:32 +0100
> Francesc Alted wrote:
>
> > What puzzles me is that the timeit loops access `z` data 3*1
> > times, which is plenty of time for doing the allocation (just
> > should
> > require just a single itera
On Wed, Jan 19, 2022 at 7:48 PM Francesc Alted wrote:
> On Wed, Jan 19, 2022 at 6:58 PM Stanley Seibert
> wrote:
>
>> Given that this seems to be Linux only, is this related to how glibc does
>> large allocations (>128kB) using mmap()?
>>
>> https://stackoverflow.com/a/33131385
>>
>
> That's a g
On Thu, 2022-01-20 at 14:41 +0100, Francesc Alted wrote:
> On Wed, Jan 19, 2022 at 7:48 PM Francesc Alted
> wrote:
>
> > On Wed, Jan 19, 2022 at 6:58 PM Stanley Seibert
> >
> > wrote:
> >
> > > Given that this seems to be Linux only, is this related to how
> > > glibc does
> > > large allocatio
On Thu, Jan 20, 2022 at 4:10 PM Sebastian Berg
wrote:
> Thanks for figuring this out! It has been bugging me a lot before. So
> it rather depends on how `malloc` works, and not the kernel. It is
> surprising how "random" this can look, but I suppose some examples just
> happen to sit almost e
On 1/20/22, Francesc Alted wrote:
> On Wed, Jan 19, 2022 at 7:48 PM Francesc Alted wrote:
>
>> On Wed, Jan 19, 2022 at 6:58 PM Stanley Seibert
>> wrote:
>>
>>> Given that this seems to be Linux only, is this related to how glibc
>>> does
>>> large allocations (>128kB) using mmap()?
>>>
>>> https
On Mon, Jan 24, 2022 at 2:15 AM Warren Weckesser
wrote:
> Thanks Sebastian for pointing out that the issue is (minor) page
> faults, and thanks Francesc for providing the links and the analysis
> of the situation. After reading those links and experimenting with
> malloc in a couple C programs,
On Mon, Jan 24, 2022 at 10:02 AM Francesc Alted wrote:
> Thanks for going down to the rabbit hole. It is now much clearer what's
> going on.
>
> All in all, hats off to Warren for this entertaining piece of
> investigation!
>
I can't resist. You'd expect someone called
https://en.wikipedia.or
On Mon, Jan 24, 2022 at 11:01 AM Francesc Alted wrote:
> On Mon, Jan 24, 2022 at 2:15 AM Warren Weckesser <
> warren.weckes...@gmail.com> wrote:
>
>> Thanks Sebastian for pointing out that the issue is (minor) page
>> faults, and thanks Francesc for providing the links and the analysis
>> of the
On Mon, Jan 24, 2022 at 1:42 PM Francesc Alted wrote:
> On Mon, Jan 24, 2022 at 11:01 AM Francesc Alted wrote:
>
>> On Mon, Jan 24, 2022 at 2:15 AM Warren Weckesser <
>> warren.weckes...@gmail.com> wrote:
>>
>>> Thanks Sebastian for pointing out that the issue is (minor) page
>>> faults, and tha
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