From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!news.glorb.com!peer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!Xl.tags.giganews.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Fri, 19 Dec 2014 13:43:44 -0600 Newsgroups: comp.lang.ada Date: Fri, 19 Dec 2014 14:43:43 -0500 From: Peter Chapin X-X-Sender: pcc09070@WIL414CHAPIN.vtc.vsc.edu Subject: =?ISO-8859-15?Q?Re=3A_GNAT=A0and_Tasklets?= In-Reply-To: <1r2ziulc78imb$.ad6zx5upic6s$.dlg@40tude.net> Message-ID: References: <8277a521-7317-4839-b0b6-97f8155be1a4@googlegroups.com> <9e1d2b9f-1b97-4679-8eec-5ba75f3c357c@googlegroups.com> <478c81f9-5233-4ae1-a3eb-e67c4dbd0da1@googlegroups.com> <1r2ziulc78imb$.ad6zx5upic6s$.dlg@40tude.net> User-Agent: Alpine 2.11 (CYG 23 2013-08-11) Organization: Vermont Technical College MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-4yOJr3v5ODqD6hQ3kAxVoEVCi2xamv1QIKOSlOnglBgWka9VkNpnSRPQJS+iCpiqnjGypSbHsmsyiwQ!Wf/rPx4TSp/TaTdDw64Z/kgeX2i12yqYIRWrdACkx0gmi3VEGgYF1wiBTszYMJs+x9w/5JRcodvx!HtvUbk0Qgi7olv8JAQ== X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 2814 X-Received-Bytes: 2926 X-Received-Body-CRC: 2451159565 Xref: news.eternal-september.org comp.lang.ada:24159 Date: 2014-12-19T14:43:43-05:00 List-Id: On Fri, 19 Dec 2014, Dmitry A. Kazakov wrote: >> For multicore, the idea is to make better use of the cores when doing >> so will improve performance. > > I don't think multi-core would bring any advantage. Starting / > activating / reusing / feeding / re-synchronizing threads is too > expensive. > > Parallel loops could be useful on some massively vectorized > architectures in some very specialized form, or on architectures with > practically infinite number of cores (e.g. molecular computers). Anyway > feeding threads with inputs and gathering outputs may still mean more > overhead than any gain. I've written some numerical programs using OpenMP and in one particularly dramatic case I acheived a speed up of nearly 4 (about 3.98) on a quad core system by marking a single critical loop as parallel. I made no other changes. Literally it was a one line change to my sequential program. The program was not particularly odd, nor was the hardware I was using. So there is definitely a benefit to be had in some cases with parallel loops. Peter