-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 12/27/2011 10:20 AM, Mike Galbraith wrote: > > Quoting removal commit af5ab277ded04bd9bc6b048c5a2f0e7d70ef0867 > Historically, Linux has tried to make the regular timer tick on > the various CPUs not happen at the same time, to avoid contention > on xtime_lock. > > Nowadays, with the tickless kernel, this contention no longer > happens since time keeping and updating are done differently. In > addition, this skew is actually hurting power consumption in a > measurable way on many-core systems. End quote > > Contention remains a problem if NO_HZ is either not configured, or > is nohz=off disabled due to workload constraints. The RT kernel > running nohz=off was measured to be using > 1.4% CPU just ticking > 64 CPUs, with tick perturbation reaching ~80us. For loads where > measured (>100us) NO_HZ latencies are intolerable, a must have. I think we need to just say no to this, and kill the nohz=off option entirely. Seriously, are people still running with ticks for any legitimate reasons? (and not just because they goofed their config file) -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (MingW32) iQEcBAEBAgAGBQJO+xpVAAoJEEHdSxh4DVnEMvUH/A5qOO+igivDtdEjw5b39w3h 4fG7VLiyn34+AAFmBqfgx9dKbl4DkYzBBRYXcNVnicnjqnH7ZZ+FOvFo2zOCUiGG xeDNox4hcl1jJ/6J1o6p1ecJXOUlbwNsXF9SVG38HPpJ4D0mgllAdy1wHJfv3+LA Ad98sUDmhq2gpcjyupvv7exIor1i3JFo/Q+CFbDTVQrgz99zo/D2IX3ps4wRfhHq q0rKcU4ZZJVHeHkItHOyEgeex9RPGlxNRSUu50zIHKugVlH9wbTtIzBkPzt1Nn0S yThyQGd/xcFfQDaiwymWLf78d6wpEZ/BW+QIlPlO2xNMD/Qz980w86yyh0x2FQk= =yDHd -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
