Re: Run time gadget2 vs. gadget4

From: Xiaolong Du <>
Date: Sat, 10 Sep 2022 05:43:51 -0700

Hi Rui,

I have seen similar things when comparing Gadget 2 and Gadget 4. It seems that if one switches on PMGRID, Gadget 4 tends to update the long range force more frequently than Gadget 2. Maybe that explains why Gadget 4 took more time. One thing you can check is the time for PM computation in the log file cpu.txt.


> On Sep 10, 2022, at 12:49 AM, HU, Rui <> wrote:
> Hi all,
> I am try to use the same IC (generated by 2LPTic), same setting and same threads in gadget2 and gadget4. Then I found gadget4 (2300s for 16 threads) is almost twice as slow as gadget2 (1226s for 16 threads). Is that because gadget4 do not do the merge and do two half-step kicks? Or maybe I misunderstand the Figure 61 in the Gadget4-code paper?
> Bests,
> Rui
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Received on 2022-09-10 14:44:04

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