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by apetresc 3398 days ago
Does anyone have any intuition around how this affects a variety of typical workflows? I imagine that these two syscalls are disproportionally likely to affect benchmarks more than real-world usage. How many times is this syscall happening on a system doing things like serving HTTP, or running batch jobs, or hosting a database, etc?
2 comments

You can use strace and see!

Go to your staging environment, use `strace -f -c -p $PID -e trace=clock_gettime` (or don't use -p and just launch the binary directly), replay a bit of production traffic against it, and then interrupt it and check the summary.

HTTP servers typically return a date header, often internally dates are used to figure out expiration and caching, and logging almost always includes dates.

It's incredibly easy to check the numbers of syscalls with strace, so you really should be able to get an intuition fairly easily by just playing around in staging.

> hosting a database

this will very likely be calling time related system calls, especially clock_gettime with CLOCK_MONOTONIC.