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From: | Paolo Bonzini |
Subject: | Re: [PATCH 2/3] ci: do not use #processors+1 jobs, #processors is enough |
Date: | Tue, 18 May 2021 14:30:04 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 |
On 18/05/21 12:49, Thomas Huth wrote:
- - JOBS=$(expr $(nproc) + 1) + - JOBS=$(nproc || echo 1)The basic idea of the "+ 1" was to make sure that there is always a thread that runs on a CPU while maybe another one is waiting for I/O to complete.
Ah, I see. It doesn't make much sense for "make check" jobs however, which is where I wanted to get with the next patch.
I'm not sure it's even true anymore with current build machines (which tend to have a large buffer cache for headers) and optimizing compilers that compilation is I/O bound, so I'll time the two and see if there is an actual difference.
Paolo This is suggested by various sites on the web, e.g.:
https://unix.stackexchange.com/questions/519092/what-is-the-logic-of-using-nproc-1-in-make-commandSo not sure whether this patch here make sense ... I'd rather drop it.
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