From 35263d6a485f953fdb39d192ce0c0c89997ae131 Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Fri, 11 Apr 2014 18:26:08 +0000 Subject: [PATCH] Improve use of socket buffer upcalls. Use soreadable()/sowriteable() in socket upcalls to avoid extra wakeups until we have enough data to read or space to write. Increase partial receive len from 1K to 128K to not wake up on every received packet. This significantly reduces locks congestion and CPU usage and improves throughput for large I/Os on NICs without TSO and LRO. Reviewed by: trasz Sponsored by: iXsystems, Inc. --- sys/dev/iscsi/icl.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/sys/dev/iscsi/icl.c b/sys/dev/iscsi/icl.c index 98d5d6d68a2..3f7cdd23787 100644 --- a/sys/dev/iscsi/icl.c +++ b/sys/dev/iscsi/icl.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include #include @@ -67,7 +68,7 @@ static int coalesce = 1; TUNABLE_INT("kern.icl.coalesce", &coalesce); SYSCTL_INT(_kern_icl, OID_AUTO, coalesce, CTLFLAG_RWTUN, &coalesce, 1, "Try to coalesce PDUs before sending"); -static int partial_receive_len = 1 * 1024; /* XXX: More? */ +static int partial_receive_len = 128 * 1024; TUNABLE_INT("kern.icl.partial_receive_len", &partial_receive_len); SYSCTL_INT(_kern_icl, OID_AUTO, partial_receive_len, CTLFLAG_RWTUN, &partial_receive_len, 1 * 1024, "Minimum read size for partially received " @@ -750,12 +751,19 @@ icl_receive_thread(void *arg) break; } + /* + * Set the low watermark, to be checked by + * soreadable() in icl_soupcall_receive() + * to avoid unneccessary wakeups until there + * is enough data received to read the PDU. + */ SOCKBUF_LOCK(&so->so_rcv); available = so->so_rcv.sb_cc; if (available < ic->ic_receive_len) { so->so_rcv.sb_lowat = ic->ic_receive_len; cv_wait(&ic->ic_receive_cv, &so->so_rcv.sb_mtx); - } + } else + so->so_rcv.sb_lowat = so->so_rcv.sb_hiwat + 1; SOCKBUF_UNLOCK(&so->so_rcv); icl_conn_receive_pdus(ic, available); @@ -772,6 +780,9 @@ icl_soupcall_receive(struct socket *so, void *arg, int waitflag) { struct icl_conn *ic; + if (!soreadable(so)) + return (SU_OK); + ic = arg; cv_signal(&ic->ic_receive_cv); return (SU_OK); @@ -854,10 +865,10 @@ icl_conn_send_pdus(struct icl_conn *ic, struct icl_pdu_stailq *queue) available = sbspace(&so->so_snd); /* - * Notify the socket layer that it doesn't need to call - * send socket upcall for the time being. + * Notify the socket upcall that we don't need wakeups + * for the time being. */ - so->so_snd.sb_lowat = so->so_snd.sb_hiwat; + so->so_snd.sb_lowat = so->so_snd.sb_hiwat + 1; SOCKBUF_UNLOCK(&so->so_snd); while (!STAILQ_EMPTY(queue)) { @@ -873,7 +884,8 @@ icl_conn_send_pdus(struct icl_conn *ic, struct icl_pdu_stailq *queue) #endif /* - * Set the low watermark on the socket, + * Set the low watermark, to be checked by + * sowritable() in icl_soupcall_send() * to avoid unneccessary wakeups until there * is enough space for the PDU to fit. */ @@ -1016,6 +1028,9 @@ icl_soupcall_send(struct socket *so, void *arg, int waitflag) { struct icl_conn *ic; + if (!sowriteable(so)) + return (SU_OK); + ic = arg; ICL_CONN_LOCK(ic);