Messages in this thread | | | Date | Sun, 14 Mar 2004 16:37:52 +0200 | From | Micha Feigin <> | Subject | Re: finding out the value of HZ from userspace |
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On Sat, Mar 13, 2004 at 05:49:29PM -0800, Andrew Morton wrote: > Micha Feigin <michf@post.tau.ac.il> wrote: > > > > > Wrong. Any such interface is supposed to convert automatically. Any > > > interface you can find that doesn't should be reported as a serious bug! > > > > > > > Like I said, look at bdflush in 2.4 (this was fixed with the changed 2.6 > > interface) and xfs proc interface in both 2.4 and 2.6. > > In light of your post then there is a serious bug. > > > > For example for bdflush age_buffer field (true for the other used fields > > also), no conversion: > > bh->b_flushtime = jiffies + bdf_prm.b_un.age_buffer; > > I doubt if there's any motivation to fix these things in 2.4. If you change > HZ in 2.4 you own both pieces. (alpha has HZ=1024 in 2.4, so presumably > bdflush tuning doesn't work right). >
There is for laptop mode which is now in the kernel so a generic startup script can be written.
I will right a patch and post it in a new thread and see how it takes.
> In 2.6, the bdflush parameters do not exist. They were replaced by > /proc/sys/vm/*_centisecs, which are HZ-independent. > > There are, I think, still some /proc tunables in 2.6 which do depend upon > HZ and they should be found and fixed. If the same tunables are present in > 2.4 kernels then they should be converted to take centiseconds in 2.6, so > 2.4-based tools continue to work correctly. > > We have similar problems where /proc tunables are expressed in terms of > "number of pages". As PAGE_SIZE varies from 4096 to 65536 this is > sometimes wrong. Fixing this is more subtle. > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > > +++++++++++++++++++++++++++++++++++++++++++ > This Mail Was Scanned By Mail-seCure System > at the Tel-Aviv University CC. > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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