(2012/06/28 15:23), KOSAKI Motohiro wrote:
On Tue, Jun 26, 2012 at 5:37 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
https://bugzilla.kernel.org/show_bug.cgi?id=43811
lru_add_drain_all() uses schedule_on_each_cpu(). But
schedule_on_each_cpu() hangs if a realtime thread is spinning, pinned
to a CPU. There's no intention to change the scheduler behaviour, so I
think we should remove schedule_on_each_cpu() from the kernel.
The biggest user of schedule_on_each_cpu() is lru_add_drain_all().
Does anyone have any thoughts on how we can do this? The obvious
approach is to declare these:
static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
to be irq-safe and use on_each_cpu(). lru_rotate_pvecs is already
irq-safe and converting lru_add_pvecs and lru_deactivate_pvecs looks
pretty simple.
Thoughts?
I agree.
But i hope more. In these days, we have plenty lru_add_drain_all()
callsite. So,
i think we should remove struct pagevec and should aim migration aware new
batch mechanism. maybe. This also improve compaction success rate.
migration-aware means an framework which isolate_xxxx_page() can work with ?
To do that, we need to know which object points to the page. Hmm. Do you have
anyidea ?
-Kame
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