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A comment on A 40-line fix eliminated a 400x performance gap. Parent comment

Re:A 40-line fix eliminated a 400x performance gap by nly on Wednesday January 14, 2026 @04:04AM (#46613902)
Why do you need a seqlock? To make sure you're not context switched out between the read of the page value and the rdtsc?

Presumably you mean you just double check the page value after the rdtsc to make sure it hasn't changed and retry if it has?

Tbh I thought clock_gettime was a vdso based virtual syscall anyway

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Re:A 40-line fix eliminated a 400x performance gap by ot on Thursday January 15, 2026 @12:08PM (#46635673)
> Presumably you mean you just double check the page value after the rdtsc to make sure it hasn't changed and retry if it has?

Yes, that's exactly what a seqlock (reader) is.

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