Jeff Garzik wrote:
Tejun Heo wrote:
Hello, all.
This is the first take of prep-for-hotplug-support patchset. As the
name suggests, this patchset prepares libata for hotplug support.
This patchset contains 15 patches.
#01-02 update sata_sil (hotplug related constants, new interrupt
handler)
#03-04 misc libata preps
#05-12 prepare ata_bus_probe()
#13-15 hotplug flags, extra fields, hotplug_wq
ACK, modulo the minor comments just sent.
Also, in general libata needs a rethink when it comes to workqueues.
Sometimes a single thread is more appropriate than the workqueue default
of one-thread-per-CPU. Using workqueues in the default state is quite
efficient, but can also given you a huge number of idle threads on a
$BIGNUM CPU box. Workqueues on a 16-CPU box can be pretty insane...
Yeah, Forrest pointed out the same thing and I've converted hotplug_wq
to single threaded variant, which should be enough for SCSI hotplugging.
For ata_wq, I think it's wiser to keep it multi-threaded for the time
being. Maybe what should be done is to allocate a single threaded
workqueue per host_set.
$BIGNUM CPU boxes tend to have $BIGNUM GB of memories, so multithreaded
wq might not be that critical resource-wise. But, still, inefficient
and doesn't scale well.
--
tejun
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