Hello! What value of HZ option would you recommend for a hosting (web) server with a lot of processes (about 900) and polling off (as decided from previous discussion polling is useless in this situation). What parts of kernel does this option affect? What depends on it? -- Regards, Artem
Artem Kuchin <> wrote: > What value of HZ option would you recommend > for a hosting (web) server with a lot of processes > (about 900) and polling off (as decided from previous > discussion polling is useless in > this situation). In that case, I would recommend not to override the default at all (which is 1000). > What parts of kernel does this option affect? What > depends on it? The value of HZ specifies the minimum timing quantum of the kernel. It affects the granularity of the scheduler and all timing-related functions (nanosleep(2) and others), and the accuracy of dummynet and polling. I'm sure there are more things. Basically, the kernel cannot handle time slices smaller than 1/HZ seconds, for any purpose. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Gesch?ftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht M?n- chen, HRB 125758, Gesch?ftsf?hrer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.
Oliver Fromme wrote:> Artem Kuchin <> wrote: >> What value of HZ option would you recommend >> for a hosting (web) server with a lot of processes >> (about 900) and polling off (as decided from previous >> discussion polling is useless in >> this situation). > > In that case, I would recommend not to override the > default at all (which is 1000).Umm.. default is 100 (one hundred), i think. -- Regards, Artem
On Wed, 3 Oct 2007, Artem Kuchin wrote:> Hello! > > What value of HZ option would you recommend for a hosting (web) server > with a lot of processes (about 900) and polling off (as decided from > previous discussion polling is useless in this situation).Is this an SMP system? If so you'd probably be well served by testing the latest 7.0-current (which will soon be a beta for 7.0-release) with the ULE scheduler. That's likely to have more benefit for you than changing HZ, although setting it to 100 is probably going to be better than 1000 for reasons others have already mentioned. hth, Doug -- This .signature sanitized for your protection