Re: Optional MPSAFE syscalls aren't
John Baldwin <[email protected]>
| Newsgroups | gmane.os.freebsd.current,gmane.os.freebsd.devel.smp |
|---|---|
| Message-ID | <[email protected]> |
On Sunday 11 June 2006 16:41, Kris Kennaway wrote: > rwatson, pjd and I tracked down the following problem when looking at > postgresql profiling traces: > > For syscalls that are part of subsystems that may be loaded from kld, > the SYSCALL_MODULE_HELPER() spams the copy of the sysent from > syscalls.master - and it never sets the SYF_MPSAFE flag. This means > that regardless of what syscalls.master says about mpsafety, such > syscalls always acquire Giant. > > One sad consequence of this is that when I removed the > SYSCALL_MODULE_HELPERs from sysv_sem.c to get rid of the bogus Giant > locking that seems to be hurting performance, postgresql hangs when > trying to start; possibly the locking in sysv_sem.c is just broken > since it was always implicitly serialized by Giant, so never in fact > tested at all. > > Apart from the SYSV IPC syscalls, this also affects the AIO and mqueue > code. I actually plan to just remove the SYF_MPSAFE flag soon anyways and just push Giant down manually into the handful of syscalls that still need it. -- John Baldwin _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "[email protected]"