Hi,all
I have long known that deadline is read-prefered. but a simple test gives
the opposite result.
with two processes running at the same time,one for read and one for
write.actually,they did nothing bug IO operation.
while(true)
{
read();
}
the other:
while(true)
{
write();
}
with deadline IO-sched and ext4 filesystem.as a result, read ratio was
about below 3M/s.and write about 100M/s. I have tested both kernel-2.6.18
and kernel-2.6.32,getting the same result.
I add some debug information in the kernel and recompile,found that,it
has little to do with IO-sched layer because read request dropped into
deadline was 5% of write request .from /proc/<pid>/stack,the read process
hands on sync_page most of the time.
what is the matter ? anyone help me ?
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