Messages in this thread | | | From | Kyle Moffett <> | Subject | Re: [PATCH] s390: Hypervisor File System | Date | Tue, 2 May 2006 19:18:52 -0400 |
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On May 2, 2006, at 17:49:08, Kay Sievers wrote: > If you can assume that processes accessing the values are > cooperative, it already works without any changes: > > $ time flock /sys/class/firmware echo 1 > /sys/class/firmware/ > timeout > real 0m0.005s > > $ flock /sys/class/firmware sleep 5& > [1] 6468 > > $ time flock /sys/class/firmware echo 1 > /sys/class/firmware/ > timeout > real 0m3.558s
But that doesn't solve the problem for framebuffer devices or for the s390 code. Such transactions have one or more of the following properties:
(1) A read operation is _expensive_ or adds unacceptable latencies and should be done as rarely as possible (2) The data must be all written to hardware simultaneously by the kernel; a partial update does not make sense and would cause undesired operation from the hardware.
The idea with the transactions would be to create a kernel-memory buffer-layer of sorts on top of the underlying sysfs tree to cache the read data and collect writes for an atomic commit. I'll see if I can make something work.
Cheers, Kyle Moffett - 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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