Messages in this thread | | | Date | Tue, 12 Dec 2006 07:56:35 +0100 | From | Eric Dumazet <> | Subject | Re: [PATCH] Introduce jiffies_32 and related compare functions |
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David Miller a écrit : > From: Eric Dumazet <dada1@cosmosbay.com> > Date: Tue, 12 Dec 2006 05:09:23 +0100 > >> We definitly *like* being able to use bigger timeouts on 64bits platforms. >> >> Not that they are mandatory since the same application should run fine on >> 32bits kernel. But as the standard type for 'tick timestamps' is 'unsigned >> long', a change would be invasive. >> >> Maybe some applications are now relying on being able to >> sleep()/select()/poll() for periods > 30 days and only run on 64 >> bits kernels. > > I think one possible target would be struct timer, at least > in theory. > > There is also a line of reasoning that says that on 64-bit > platforms we have some flexibility to set HZ very large, if > we wanted to at some point, and going to 32-bit jiffies > storage for some things may eliminate that kind of flexibility. >
Yes good point, and my understanding is that we go for a tickless kernel in 2.6.21, or so. I wonder if virtual HZ wont be sticked to a low value.
I suspect in the case HZ raises, we switch some/most uses of jiffies_32 to another variable (xtime_32 or whatever), but keep the storage on 32bits...
But keeping 64bits values 'just because hardware allows us this kind of expenditure' seems not reasonable to me, but lazy...
Eric
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