[CRIU] [PATCH 0/15] Buffered images IO

[Pavel Emelyanov]

Hi

Recent experiments show, that we spend too much time in writing
and reading images. E.g. for dump strace shows that we spend most
of the time logging (with -v4) and writing images. On restore we
wait for other tasks to do it (only spoils the parallel restore)
and, yet again, reading from images.

This is because we use write() and read() for every single object.
For on-disk FS this it too time consuming even when using the
std Linux page cache -- small IO-s take little time to get
memcpy-d and a lot of time for FS preparations (especially writes).

So this is a set that uses the recently added bfd engine for
images IO. On dump this removes ~14% of time for p.haul test and
for restore it removes ~3K read() calls our of ~4.5K (hard to
estimate the time percentage since we're in multi-process mode 
there).

Thanks,
Pavel