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Improve performance by changing the behavour of the driver when all
SDMA descriptors are in use, and the processes adding new descriptors
are single- or multi-rail.
For single-rail processes, the driver will block the call and finish
posting all SDMA descriptors onto the hardware queue before returning
back to PSM. Repeated kernel calls are slower than blocking.
For multi-rail processes, the driver will return to PSM as quick as
possible so PSM can feed packets to other rail. If all hardware
queues are full, PSM will buffer the remaining SDMA descriptors until
notified by interrupt that space is available.
This patch builds a red-black tree to track the number rails opened by
a particular PID. If the number is more than one, it is a multi-rail
PSM process, otherwise, it is a single-rail process.
Reviewed-by: Dean Luick <dean.luick@intel.com>
Reviewed-by: John A Gregor <john.a.gregor@intel.com>
Reviewed-by: Mitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: CQ Tang <cq.tang@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
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qib_user_sdma_queue_pkts() gets called with mmap_sem held for
writing. Except for get_user_pages() deep down in
qib_user_sdma_pin_pages() we don't seem to need mmap_sem at all. Even
more interestingly the function qib_user_sdma_queue_pkts() (and also
qib_user_sdma_coalesce() called somewhat later) call copy_from_user()
which can hit a page fault and we deadlock on trying to get mmap_sem
when handling that fault.
So just make qib_user_sdma_pin_pages() use get_user_pages_fast() and
leave mmap_sem locking for mm.
This deadlock has actually been observed in the wild when the node
is under memory pressure.
Cc: <stable@vger.kernel.org>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Roland Dreier <roland@purestorage.com>
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1. The code accepts chunks of messages, and splits the chunk into
packets when converting packets into sdma queue entries. Adjacent
packets will use user buffer pages smartly to avoid pinning the
same page multiple times.
2. Instead of discarding all the work when SDMA queue is full, the
work is saved in a pending queue. Whenever there are enough SDMA
queue free entries, pending queue is directly put onto SDMA queue.
3. An interrupt handler is used to progress this pending queue.
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: CQ Tang <cq.tang@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
[ Fixed up sparse warnings. - Roland ]
Signed-off-by: Roland Dreier <roland@purestorage.com>
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Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
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Reset the list pointers after freeing the SDMA packet list. This is
done to any potential double-free cases.
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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Add a low-level IB driver for QLogic PCIe adapters.
Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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