Also - I read in a couple of places online that if you have OpenCL support enabled then the CPU threading stops.
I can't test that to see if it is true because I can't seem to get OpenCL to work on this Linux desktop. Trying it on a Windows machine should answer that question. On Thu, Apr 23, 2020 at 4:56 PM Drew Jensen <drewjensen.in...@gmail.com> wrote: > To follow up on that. > > Using LO 6.4 & 7.0 pre-release build on Ubuntu. Recalculating one of the > OpenCL test xls files just now. > > Starting up with a command line > MAX_CONCURRENCY=0 ./soffice > Does turn the CPU threading off. > > Restarting with a command line > MAX_CONCURRENCY=4 ./soffice > Turns it back on (for my AMD a5800 processor this will give me two > threads, because while the CPU is called a 4 core processor and it does > have 4 accumulators it only has 2 floatingpoint cores and this is the > limiting factor it seems) with recalculation time for the workbook is ~2x > faster. > > > On Thu, Apr 23, 2020 at 1:48 PM Drew Jensen <drewjensen.in...@gmail.com> > wrote: > >> 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...@gmail.com> wrote: >> >>> Mike and Luboš, >>> >>> Many thanks for your help on this topic. >>> >>> Regards, >>> >>> Steve >>> >>> On Thu, 23 Apr 2020 at 11:16, Mike Kaganski <mikekagan...@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 >>>> >>> _______________________________________________ >>> LibreOffice mailing list >>> LibreOffice@lists.freedesktop.org >>> https://lists.freedesktop.org/mailman/listinfo/libreoffice >>> >>
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