Re: Using shared memory and thread
On Monday, 4 November 2019 at 19:53:29 UTC, bioinfornatics wrote: 3/ variable flagged as `shared` does at mean the variable is put into L2 cache ? First caching is controlled by CPU not programmer. Second not all architectures share L2 between cores. 4 jaguar cores share L2 cache in consoles https://images.anandtech.com/doci/6976/Screen%20Shot%202013-05-23%20at%2012.22.12%20AM_678x452.png 2 bulldozer cores share L2 cache in FX processors https://s3.amazonaws.com/hs-wordpress/wp-content/uploads/2017/12/13035240/bulldozer_021.jpg each zen core has its own L2 cache in Ryzen cpu's https://images.anandtech.com/doci/10591/HC28.AMD.Mike%20Clark.final-page-014.jpg Third your link to run.dlang is 404 While you cant control cache contents explicitly you can control it by changing memory access patterns. When you fetch a peace of data CPU will load 64 byte size bucket/chunk that contains your data into L1 cache. Since L1 cache size is limited CPU had to remove existing data from L1 based on its eviction policy. Evicted data goes into L2 cache. That is the way to control what is where. By default all variables(except immutable or static) are thread local and can only be accessed by one thread. Shared keyword makes data accessible trough multiple threads
Re: Using shared memory and thread
On Tuesday, 5 November 2019 at 00:07:40 UTC, bioinfornatics wrote: On Tuesday, 5 November 2019 at 00:04:05 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 22:19:29 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 21:53:45 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 19:53:29 UTC, bioinfornatics wrote: [...] One image reveals more than a thousand words, see my picture :-) -> http://pix.toile-libre.org/?img=1572906675.png oups got a problem with the alpha layer: -> http://pix.toile-libre.org/?img=1572908302.png here my (not working) snippet code: -> https://run.dlang.io/gist/75429dcb8612e00635f7d53aabc4776f the example do not meet exactly the spec and he do not compile. arf the generated link raise a 404, here a gist I got some help from `feep` on IRC and he show me that the task pool can not to be const as reduce is not. So now I have this script: > https://gist.github.com/run-dlang/46c753f7233a624bb5639db615c9634a And this error: > /dlang/dmd/linux/bin64/../../src/phobos/std/parallelism.d(2730): Error: function std.parallelism.TaskPool.reduce!"a + b".reduce!(MapResult!(__lambda3, Result)).reduce cannot get frame pointer to onlineapp.countAllLines I found this thread which talk about this error, but that did not help me to fix it: https://github.com/dlang/phobos/pull/4915 Thanks for your help https://gist.github.com/run-dlang/4ffcc0641acef5eedf52a17c4995599b
Re: Using shared memory and thread
On Tuesday, 5 November 2019 at 00:04:05 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 22:19:29 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 21:53:45 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 19:53:29 UTC, bioinfornatics wrote: [...] One image reveals more than a thousand words, see my picture :-) -> http://pix.toile-libre.org/?img=1572906675.png oups got a problem with the alpha layer: -> http://pix.toile-libre.org/?img=1572908302.png here my (not working) snippet code: -> https://run.dlang.io/gist/75429dcb8612e00635f7d53aabc4776f the example do not meet exactly the spec and he do not compile. arf the generated link raise a 404, here a gist https://gist.github.com/run-dlang/4ffcc0641acef5eedf52a17c4995599b
Re: Using shared memory and thread
On Monday, 4 November 2019 at 22:19:29 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 21:53:45 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 19:53:29 UTC, bioinfornatics wrote: Dear, I would like to put a buffer `shared(char[])` into a shared memory ( L2 cache ) and provide a start and end index to multiple thread in order to perform computation on a piece of original buffer. [...] One image reveals more than a thousand words, see my picture :-) -> http://pix.toile-libre.org/?img=1572906675.png oups got a problem with the alpha layer: -> http://pix.toile-libre.org/?img=1572908302.png here my (not working) snippet code: -> https://run.dlang.io/gist/75429dcb8612e00635f7d53aabc4776f the example do not meet exactly the spec and he do not compile.
Re: Using shared memory and thread
On Monday, 4 November 2019 at 21:53:45 UTC, bioinfornatics wrote: On Monday, 4 November 2019 at 19:53:29 UTC, bioinfornatics wrote: Dear, I would like to put a buffer `shared(char[])` into a shared memory ( L2 cache ) and provide a start and end index to multiple thread in order to perform computation on a piece of original buffer. [...] One image reveals more than a thousand words, see my picture :-) -> http://pix.toile-libre.org/?img=1572906675.png oups got a problem with the alpha layer: -> http://pix.toile-libre.org/?img=1572908302.png
Re: Using shared memory and thread
On Monday, 4 November 2019 at 19:53:29 UTC, bioinfornatics wrote: Dear, I would like to put a buffer `shared(char[])` into a shared memory ( L2 cache ) and provide a start and end index to multiple thread in order to perform computation on a piece of original buffer. [...] One image reveals more than a thousand words, see my picture :-) -> http://pix.toile-libre.org/?img=1572906675.png
