Rahul Lakkireddy e92a0e7fba cxgb4: fix throughput drop during Tx backpressure
[ Upstream commit 7affd80802afb6ca92dba47d768632fbde365241 ]

commit 7c3bebc3d868 ("cxgb4: request the TX CIDX updates to status page")
reverted back to getting Tx CIDX updates via DMA, instead of interrupts,
introduced by commit d429005fdf2c ("cxgb4/cxgb4vf: Add support for SGE
doorbell queue timer")

However, it missed reverting back several code changes where Tx CIDX
updates are not explicitly requested during backpressure when using
interrupt mode. These missed changes cause slow recovery during
backpressure because the corresponding interrupt no longer comes and
hence results in Tx throughput drop.

So, revert back these missed code changes, as well, which will allow
explicitly requesting Tx CIDX updates when backpressure happens.
This enables the corresponding interrupt with Tx CIDX update message
to get generated and hence speed up recovery and restore back
throughput.

Fixes: 7c3bebc3d868 ("cxgb4: request the TX CIDX updates to status page")
Fixes: d429005fdf2c ("cxgb4/cxgb4vf: Add support for SGE doorbell queue timer")
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-01 11:01:30 +02:00
2020-03-25 08:25:58 +01:00
2020-03-05 16:43:47 +01:00
2020-03-25 08:25:58 +01:00
2020-03-25 08:25:58 +01:00
2019-09-22 10:34:46 -07:00
2019-11-10 13:41:59 -08:00
2020-03-25 08:26:00 +01:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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