Fwd: [libreoffice-documentation] Multi-threading in Calc

Drew Jensen drewjensen.inbox at gmail.com
Thu Apr 23 17:48:23 UTC 2020

BTW I'm copying a paragraph from an email on a different list.

"Also - if you set MAX_CONCURRENCY=16 - or somesuch (ie. twice your
number of threads) - you may be able to defeat the hyper-threaded
halving, and see if this workload happens to be one that does better
with hyper-threading than without."M.M.

It might be worth mentioning the MAX_CURRENCY setting for controlling CPU
thread usage.

Also, I wonder if the folks answering could answer one other question:
Does LibreOffice OnLine also use cpu threading in the same way it does when
run for desktop or headless? It would be with noting in the documentation
if it does not, IMO.

On Thu, Apr 23, 2020 at 9:56 AM Stephen Fanning <stevemfanning.wh at gmail.com>

> Mike and  Luboš,
> Many thanks for your help on this topic.
> Regards,
> Steve
> On Thu, 23 Apr 2020 at 11:16, Mike Kaganski <mikekaganski at hotmail.com>
> wrote:
>> On 23.04.2020 13:12, Luboš Luňák wrote:
>> > On Thursday 23 of April 2020, Stephen Fanning wrote:
>> >> As for the processing itself, I remain unclear about how Calc allocates
>> >> tasks to threads. Can we give the user any general advice on how he
>> could
>> >> structure his spreadsheet to gain the maximum performance benefits
>> from the
>> >> availability of multiple cores? Or maybe there are ways to organise a
>> >> spreadsheet that will frustrate Calc's attempts to multi-thread, which
>> we
>> >> ought to advise against?
>> >
>> >  Technically threads are generally used only for formula groups, which
>> are a
>> > sufficient number of adjacent cells in a column that use the same
>> formula
>> > (and get different results because of relative cell addressing). In UI
>> terms,
>> > write e.g. "=A1*2" to B1, grab the bottom-right corner of the cell and
>> extend
>> > down. But it's implementated this way because that's usually how large
>> > spreadsheets are created. So I think it's a needless complication to be
>> > specific about this.
>> >
>> IMO it's still useful to mention that the optimization is column-based.
>> Because many people don't realize that row-based layout is potentially
>> less efficient. This would be beneficial to those who don't create
>> spreadsheets according to how it's "usually" done.
>> --
>> Best regards,
>> Mike Kaganski
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