-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Filip Navara wrote:
> Jonas Maebe wrote: > >> On 25 Apr 2005, at 22:17, Massimo Dal Zotto wrote: >> >>> In the meantime until we find a better solution could you give >>> us some explanation on why using a microseconds clock from >>> gettimeofday instead of rdtsc the guest os clock runs always >>> 20% slower? >> >> >> Because a system call (which gettimeofday is) is very slow (two >> context switches). > > > I remember there was a Linux patch which changed the gettimeofday > function to read the info from user mode shared page (which is > updated by the kernel) and thus avoided the syscall overhead. Not > sure if/when it was integrated into the official sources... > > (Once again Windows NT were ahead of time with this idea > implemented way earlier ;-) Another *solution* is to use kernel mode linux =). See http://web.yl.is.s.u-tokyo.ac.jp/~tosh/kml/ It makes already low Linux syscall overhead much lower. Tara -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFCbXMfmzwUPloTW30RAg+7AKCh0jGnYhvRp0/qtwm36wXDrCxd2ACgpdMi LBQsxo56m98yPvkAPFJ0PAQ= =jpKR -----END PGP SIGNATURE----- _______________________________________________ Qemu-devel mailing list Qemu-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/qemu-devel
