Excessive CPU use

[tpoppins]

Like its predecessor, v0.4.0, Barbarossa 0.5.0 uses more CPU than a typical single-threaded program.

For example, on this 12-core system Task Manager reports 8% CPU use for non-SMP applications. Barbarossa's use fluctuates between 10% and 11%. This is over 25% more than a single-threaded application is expected to use and can wreck tests where multiple concurrent games are run at the same time.

My test boxes are various dual Xeons running Cute Chess GUI under Win 7 x64 Pro SP1. Graham reports the same issue with ChessGUI under Win 10.

Tirsa@CCRL

[nionita]

Hi Tirsa, Barbarossa is written in Haskell, and this language has a garbage collector, which runs after the engine move has been communicated to the GUI. I am not sure this is the reson for the more CPU usage you measure, but it should be the only noticeable task except search. On the other hand there is afaik no restriction for a single threaded UCI engine to use only one OS thread for all tasks. "Single Threaded" is referring to the search task. Barbarossa has currently only one search thread. Other tasks (mainly communication with the GUI, but also logging, which actually should have very little overhead) can be done in separate OS threads. If I remember correctly, even Stockfish uses such additinal threads (But I could not find that post on talchess.com where I read this.) But anyway, if this is a problem, I could make a test version which uses only 1 OS thread for all tasks, to check that the more CPU usage you measure is comming from the garbage collection, if you want. Best regards, Nicu

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------ Originalnachricht ------ Von: "tpoppins" <[email protected]> An: "nionita/Barbarossa" <[email protected]> Cc: "Subscribed" <[email protected]> Gesendet: 12.03.2019 21:50:48 Betreff: [nionita/Barbarossa] Excessive CPU use (#2)

Like its predecessor, v0.4.0, Barbarossa 0.5.0 uses more CPU than a typical single-threaded program. For example, on this 12-core system Task Manager reports 8% CPU use for non-SMP applications. Barbarossa's use fluctuates between 10% and 11%. This is over 25% more than a single-threaded application is expected to use and can wreck tests where multiple concurrent games are run at the same time. My test boxes are various dual Xeons running Cute Chess GUI under Win 7 x64 Pro SP1. Graham reports the same issue with ChessGUI under Win 10. ***@***.*** — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#2>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABNsI4N-hNZLdXiA-GifkX4UHEFhwKgqks5vWBMngaJpZM4br2r3>.

[nionita]

Release 0.6.0 must have solved this problem, as it runs only with one OS thread at all.