RSEQ Support Might Finally Premiere In Glibc 2.31 For Using This Modern Linux Feature

[phoronix]

Phoronix: RSEQ Support Might Finally Premiere In Glibc 2.31 For Using This Modern Linux Feature

It's looking like RSEQ support might be added to the GNU C Library with the Glibc 2.31 release in a few months time. The "restartable sequences" support was added last year to the Linux kernel and the numbers have been quite promising for the performance benefits...

http://www.phoronix.com/scan.php?page=news_item&px=RSEQ-Glibc-2.31-Possible

[milkylainen]

I don't quite follow. Why would this be faster than a vDSO getcpu?
Also, wouldn't TLS-data like this be more prone to hole-pokeing than vDSO-spaces?

[pal666]

Why would this be faster than a vDSO getcpu?

because it is just one memory read. but it's not just faster, it is additionally atomic. your getcpu result is useless if you happen to be rescheduled to different cpu just before or after getcpu call. by atomic i mean whole sequence of "get cpu number and use it"