Date: Thu, 6 Oct 2016 17:22:11 -0700 From: hiren panchasara <hiren@strugglingcoder.info> To: transport@FreeBSD.org Cc: lstewart@FreeBSD.org Subject: Exiting from loss recovery Message-ID: <20161007002211.GO50669@strugglingcoder.info>
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[-- Attachment #1 --]
In tcp_do_segment():
/*
* If the congestion window was inflated to account
* for the other side's cached packets, retract it.
*/
if (IN_FASTRECOVERY(tp->t_flags)) {
if (SEQ_LT(th->th_ack, tp->snd_recover)) {
if (tp->t_flags & TF_SACK_PERMIT)
tcp_sack_partialack(tp, th);
else
tcp_newreno_partial_ack(tp, th);
} else
cc_post_recovery(tp, th);
}
Here, if we get an ack that marks recovery from loss i.e. >=
snd_recovery, we call cc_post_recovery() which in-turn calls CC specific
post_recovery routine. But we don't reset TF_FASTRECOVERY |
TF_CONGRECOVERY flags by calling EXIT_RECOVERY()
Later in the code we do this check again in 'process_ACK:'
/* XXXLAS: Can this be moved up into cc_post_recovery? */
if (IN_RECOVERY(tp->t_flags) &&
SEQ_GEQ(th->th_ack, tp->snd_recover)) {
EXIT_RECOVERY(tp->t_flags);
}
And as it can be seen, Lawrence marked it as something that could
possibly be done here and at the end of cc_post_recovery().
So, should we do it? i.e call EXIT_RECOVERY() at the end of
cc_post_recovery() and remove the block from 'process_ACK' section? or
there is something subtle I am not seeing?
Cheers,
Hiren
[-- Attachment #2 --]
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