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alistair23-linux/net/9p
Stefano Stabellini 36f9967531 9p/xen: increase XEN_9PFS_RING_ORDER
Increase XEN_9PFS_RING_ORDER to 9 for performance reason. Order 9 is the
max allowed by the protocol.

We can't assume that all backends will support order 9. The xenstore
property max-ring-page-order specifies the max order supported by the
backend. We'll use max-ring-page-order for the size of the ring.

This means that the size of the ring is not static
(XEN_FLEX_RING_SIZE(9)) anymore. Change XEN_9PFS_RING_SIZE to take an
argument and base the calculation on the order chosen at setup time.

Finally, modify p9_xen_trans.maxsize to be divided by 4 compared to the
original value. We need to divide it by 2 because we have two rings
coming off the same order allocation: the in and out rings. This was a
mistake in the original code. Also divide it further by 2 because we
don't want a single request/reply to fill up the entire ring. There can
be multiple requests/replies outstanding at any given time and if we use
the full ring with one, we risk forcing the backend to wait for the
client to read back more replies before continuing, which is not
performant.

Link: http://lkml.kernel.org/r/20200521193242.15953-1-sstabellini@kernel.org
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
2020-06-02 08:00:39 +02:00
..
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile 9p: Remove p9_idpool 2018-08-29 13:39:57 +09:00
client.c 9pnet: allow making incomplete read requests 2020-03-27 09:29:56 +00:00
error.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 188 2019-05-30 11:29:21 -07:00
mod.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 188 2019-05-30 11:29:21 -07:00
protocol.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 188 2019-05-30 11:29:21 -07:00
protocol.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 188 2019-05-30 11:29:21 -07:00
trans_common.c net/9p: include trans_common.h to fix missing prototype warning. 2018-11-20 15:04:16 +09:00
trans_common.h net/9p: remove (now-)unused helpers 2015-04-11 22:28:29 -04:00
trans_fd.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 188 2019-05-30 11:29:21 -07:00
trans_rdma.c rdma: Enable ib_alloc_cq to spread work over a device's comp_vectors 2019-08-05 11:50:32 -04:00
trans_virtio.c 9p pull request for inclusion in 5.13 2019-07-12 17:31:19 -07:00
trans_xen.c 9p/xen: increase XEN_9PFS_RING_ORDER 2020-06-02 08:00:39 +02:00