Quoting Ian McDonald:
| Folks,
|
| Here is something I've whipped up. Just wondering about your thoughts on this? I think it makes more sense to do by packets queued rather than bytes as it is a datagram based protocol.
|
| Notes:
| - Compile tested only
| - Probably won't apply to latest tree (sorry about that - will fix before I ask to merge)
|
| Appreciate feedback.
|
| This implements tx buffer sysctls for DCCP.
This is great to have! Indeed, it is very useful - without control on the tx buffer, it can
lead to much increased jitter (if too much gets blocked). Ideally, this could be a socket option
but I don't think that it is necessary now. It would be good to have this submitted. I had meant
to update it with regard to the latest change sets, but my connection is sluggish and I also need
to update the patch backlog.
If you submit this, I can take care of making it applicable to the latest changes.
Please see inline.
Gerrit
| --- a/net/dccp/dccp.h
| +++ b/net/dccp/dccp.h
| /* Time in msecs for blocking transmit per packet */
|
| +extern int sysctl_dccp_tx_qlen;
can you move the comment to the place where sysctl_dccp_tx_qlen is declared
| --- a/net/dccp/proto.c
| +++ b/net/dccp/proto.c
a comment above here would be good
| +int sysctl_dccp_tx_qlen;
| +
| +EXPORT_SYMBOL_GPL(sysctl_dccp_tx_qlen);
This can be deleted since the the variable stays local to net/dccp/proto.c (see below)
|+ sysctl_dccp_tx_qlen = 6; /* number that sounds about right */
Can you use a #define in dccp.h please (agree with the number, it seems that 5 is really the minimum)
and add descriptive text for Documentation/networking/dccp.txt, e.g.
net.dccp.default.tx_qlen = 6
The size of the transmit buffer. A value of zero corresponds to an unbounded transmit buffer;
a value of 5 is recommendable ....
/* ..... and here follows the second part of the patch */
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -634,6 +634,14 @@ int dccp_sendmsg(struct kiocb *iocb, str
return -EMSGSIZE;
lock_sock(sk);
+
+ if (sysctl_dccp_tx_qlen &&
+ (sk->sk_write_queue.qlen >= sysctl_dccp_tx_qlen)) {
+ /* if sysctl_dccp_tx_qlen == 0 then unlimited tx queue */
+ rc = -EAGAIN;
+ goto out_release;
+ }
+
timeo = sock_sndtimeo(sk, noblock);
/*
-
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