On 10/24/06, David Zeuthen <[email protected]> wrote:
b) if the kernel ensures that the 'timestamp' file is updated last,
we get atomic updates
Atomic updates require either double-buffering the data (twice worse
than mere caching...) or locking away access during update (in which
case the order doesn't mater).
But yes, lack of atomicity in sysfs is a big issue. We don't seem to
have any ABI convention for providing atomic snapshots of those
dozen-small-atribute directories.
Notably user space can see _when_ the values from the hardware was
retrieved the last time
This is a good thing, but is orthogonal to the how-do-we-poll issue.
So.. how all this relates to hwmon I'm not sure.. looking briefly at
Documentation/hwmon/sysfs-interface no such thing seems to be available,
Yes, hwmon ignores merrily ignores this issue, as do all other
data-through-sysfs drivers I've looked at. Except for the patched
hdaps driver in the tp_smapi package, which has a (very) rudimentary
solution via caching and a configurable in-kernel polling timer.
Shem
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
