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  1. Feb 05, 2022
  3. Feb 04, 2022
    • David S. Miller's avatar
      Merge branch 'ipa-RX-replenish' · c531adaf
      David S. Miller authored 
      

Alex Elder says:

====================
net: ipa: improve RX buffer replenishing

This series revises the algorithm used for replenishing receive
buffers on RX endpoints.  Currently there are two atomic variables
that track how many receive buffers can be sent to the hardware.
The new algorithm obviates the need for those, by just assuming we
always want to provide the hardware with buffers until it can hold
no more.

The first patch eliminates an atomic variable that's not required.
The next moves some code into the main replenish function's caller,
making one of the called function's arguments unnecessary.   The
next six refactor things a bit more, adding a new helper function
that allows us to eliminate an additional atomic variable.  And the
final two implement two more minor improvements.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      c531adaf
    • Alex Elder's avatar
      net: ipa: determine replenish doorbell differently · 9654d8c4
      Alex Elder authored 
      

Rather than tracking the number of receive buffer transactions that
have been submitted without a doorbell, just track the total number
of transactions that have been issued.  Then ring the doorbell when
that number modulo the replenish batch size is 0.

The effect is roughly the same, but the new count is slightly more
interesting, and this approach will someday allow the replenish
batch size to be tuned at runtime.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      9654d8c4
    • Alex Elder's avatar
      net: ipa: replenish after delivering payload · 5d6ac24f
      Alex Elder authored 
      

Replenishing is now solely driven by whether transactions are
available for a channel, and it doesn't really matter whether
we replenish before or after we deliver received packets to the
network stack.

Replenishing before delivering the payload adds a little latency.
Eliminate that by requesting a replenish after the payload is
delivered.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5d6ac24f
    • Alex Elder's avatar
      net: ipa: kill replenish_backlog · 09b337de
      Alex Elder authored 
      

We no longer use the replenish_backlog atomic variable to decide
when we've got work to do providing receive buffers to hardware.
Basically, we try to keep the hardware as full as possible, all the
time.  We keep supplying buffers until the hardware has no more
space for them.

As a result, we can get rid of the replenish_backlog field and the
atomic operations performed on it.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      09b337de
    • Alex Elder's avatar
      net: ipa: introduce gsi_channel_trans_idle() · 5fc7f9ba
      Alex Elder authored 
      

Create a new function that returns true if all transactions for a
channel are available for use.

Use it in ipa_endpoint_replenish_enable() to see whether to start
replenishing, and in ipa_endpoint_replenish() to determine whether
it's necessary after a failure to schedule delayed work to ensure a
future replenish attempt occurs.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5fc7f9ba
    • Alex Elder's avatar
      net: ipa: don't use replenish_backlog · d0ac30e7
      Alex Elder authored 
      

Rather than determining when to stop replenishing using the
replenish backlog, just stop when we have exhausted all available
transactions.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      d0ac30e7
    • Alex Elder's avatar
      net: ipa: allocate transaction in replenish loop · 6a606b90
      Alex Elder authored 
      

When replenishing, have ipa_endpoint_replenish() allocate a
transaction, and pass that to ipa_endpoint_replenish_one() to fill.
Then, if that produces no error, commit the transaction within the
replenish loop as well.  In this way we can distinguish between
transaction failures and buffer allocation/mapping failures.

Failure to allocate a transaction simply means the hardware already
has as many receive buffers as it can hold.  In that case we can
break out of the replenish loop because there's nothing more to do.

If we fail to allocate or map pages for the receive buffer, just
try again later.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      6a606b90
    • Alex Elder's avatar
      net: ipa: decide on doorbell in replenish loop · b9dbabc5
      Alex Elder authored 
      

Decide whether the doorbell should be signaled when committing a
replenish transaction in the main replenish loop, rather than in
ipa_endpoint_replenish_one().  This is a step to facilitate the
next patch.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      b9dbabc5