And I found the other reason (Re: Found one reason libibnetdisc is slower than subnet_discover)

[Ira Weiny <weiny2-i2BcT+NCU+M@public.gmane.org>]

It looks like subnet_discover was actually allowing n+1 smps on the wire.  With this patch:

diff --git a/tests/subnet_discover.c b/tests/subnet_discover.c
index acc8c23..22b092a 100644
--- a/tests/subnet_discover.c
+++ b/tests/subnet_discover.c
@@ -189,7 +189,7 @@ static void run_request_queue(int fd, int agent)
        struct request_queue *q = request_queue.next;
 
        while (q) {
-               if (outstanding > max_outstanding)
+               if (outstanding >= max_outstanding)
                        break;
                if (send_request(fd, agent, q->trid, q->path, q->path_cnt,
                                 q->attr_id, q->attr_mod) < 0)

The time for subnet_discover becomes more like libibnetdisc with the fix I sent in the email below...

10:12:15 > time ./subnet_discover -n 1 > /dev/null

real    0m2.381s
user    0m0.217s
sys     0m0.185s

Therefore, it appears that having just 2 outstanding MAD's on the wire is a huge improvement.

Ira

On Thu, 21 Jan 2010 18:14:18 -0800
Ira Weiny <weiny2-i2BcT+NCU+M@public.gmane.org> wrote:

> Sasha,
> 
> Here is a patch which speeds up libibnetdisc by about 17%.  I am not going to pursue this much because I think a major rework of the library is necessary and I like your algorithm.  I see a couple of minor issues but I think they can be worked out.
> 
> Anyway here is the data for the patch below.  This is on Hyperion the test cluster I was using before.
> 
> 17:38:26 > time ibnetdiscover --node-name-map=/etc/opensm/ib-node-name-map > old
> 
> real    0m3.174s
> user    0m0.049s
> sys     0m0.834s
> 
> 18:15:42 > time ./ibnetdiscover --node-name-map=/etc/opensm/ib-node-name-map > new
> 
> real    0m2.625s
> user    0m0.057s
> sys     0m0.570s
> 
> 18:15:49 > diff old new
> 2c2
> < # Topology file: generated on Thu Jan 21 18:15:42 2010
> ---
> > # Topology file: generated on Thu Jan 21 18:15:49 2010
> 
> 
> Ira
> 
> 
> From 53a3f1936e0ec954a3c470cc5436ce4fd6be3b3e Mon Sep 17 00:00:00 2001
> From: Ira Weiny <weiny2-ig7AzVSIIG5IWGcSWN6Auu1ftBKYq+Ku@public.gmane.org>
> Date: Thu, 21 Jan 2010 17:13:37 -0800
> Subject: [PATCH] optimize query_node
> 
>    recognize when we have found a switch we have already processed and skip the
>    SwitchInfo and NodeDescription queries.
> 
> Signed-off-by: Ira Weiny <weiny2-ig7AzVSIIG5IWGcSWN6Auu1ftBKYq+Ku@public.gmane.org>
> ---
>  infiniband-diags/libibnetdisc/src/ibnetdisc.c |   45 +++++++++++++++----------
>  1 files changed, 27 insertions(+), 18 deletions(-)
> 
> diff --git a/infiniband-diags/libibnetdisc/src/ibnetdisc.c b/infiniband-diags/libibnetdisc/src/ibnetdisc.c
> index d0c97a1..fa0dbe4 100644
> --- a/infiniband-diags/libibnetdisc/src/ibnetdisc.c
> +++ b/infiniband-diags/libibnetdisc/src/ibnetdisc.c
> @@ -101,19 +101,30 @@ static int query_node_info(struct ibmad_port *ibmad_port,
>  	return 0;
>  }
>  
> +static ibnd_node_t *find_existing_node(ibnd_fabric_t * fabric,
> +				       uint64_t guid)
> +{
> +	int hash = HASHGUID(guid) % HTSZ;
> +	ibnd_node_t *node;
> +
> +	for (node = fabric->nodestbl[hash]; node; node = node->htnext)
> +		if (node->guid == guid)
> +			return node;
> +
> +	return NULL;
> +}
> +
>  static int query_node(struct ibmad_port *ibmad_port, ibnd_fabric_t * fabric,
>  		      ibnd_node_t * node, ibnd_port_t * port,
>  		      ib_portid_t * portid)
>  {
>  	int rc = 0;
>  	void *nd = node->nodedesc;
> +	ibnd_node_t *existing;
>  
>  	if ((rc = query_node_info(ibmad_port, fabric, node, portid)) != 0)
>  		return rc;
>  
> -	if (!smp_query_via(nd, portid, IB_ATTR_NODE_DESC, 0, 0, ibmad_port))
> -		return -1;
> -
>  	if ((rc = query_port_info(ibmad_port, portid, 0, port)) != 0)
>  		return rc;
>  
> @@ -121,7 +132,7 @@ static int query_node(struct ibmad_port *ibmad_port, ibnd_fabric_t * fabric,
>  	port->guid = mad_get_field64(node->info, 0, IB_NODE_PORT_GUID_F);
>  
>  	if (node->type != IB_NODE_SWITCH)
> -		return 0;
> +		goto query_nd;
>  
>  	node->smalid = port->base_lid;
>  	node->smalmc = port->lmc;
> @@ -135,6 +146,12 @@ static int query_node(struct ibmad_port *ibmad_port, ibnd_fabric_t * fabric,
>  	port->base_lid = (uint16_t) node->smalid;	/* LID is still defined by port 0 */
>  	port->lmc = (uint8_t) node->smalmc;
>  
> +	if ((existing = find_existing_node(fabric, node->guid)) != NULL) {
> +		/* probably don't even need this memcpy */
> +		memcpy(node, existing, sizeof *node);
> +		return (0);
> +	}
> +
>  	if (!smp_query_via(node->switchinfo, portid, IB_ATTR_SWITCH_INFO, 0, 0,
>  			   ibmad_port))
>  		node->smaenhsp0 = 0;	/* assume base SP0 */
> @@ -144,6 +161,11 @@ static int query_node(struct ibmad_port *ibmad_port, ibnd_fabric_t * fabric,
>  
>  	IBND_DEBUG("portid %s: got switch node %" PRIx64 " '%s'\n",
>  		   portid2str(portid), node->guid, node->nodedesc);
> +
> +query_nd:
> +	if (!smp_query_via(nd, portid, IB_ATTR_NODE_DESC, 0, 0, ibmad_port))
> +		return -1;
> +
>  	return 0;
>  }
>  
> @@ -208,19 +230,6 @@ static void dump_endnode(ib_portid_t * path, char *prompt,
>  	       port->base_lid + (1 << port->lmc) - 1, node->nodedesc);
>  }
>  
> -static ibnd_node_t *find_existing_node(ibnd_fabric_t * fabric,
> -				       ibnd_node_t * new)
> -{
> -	int hash = HASHGUID(new->guid) % HTSZ;
> -	ibnd_node_t *node;
> -
> -	for (node = fabric->nodestbl[hash]; node; node = node->htnext)
> -		if (node->guid == new->guid)
> -			return node;
> -
> -	return NULL;
> -}
> -
>  ibnd_node_t *ibnd_find_node_guid(ibnd_fabric_t * fabric, uint64_t guid)
>  {
>  	int hash = HASHGUID(guid) % HTSZ;
> @@ -459,7 +468,7 @@ static int get_remote_node(struct ibmad_port *ibmad_port,
>  		return 1;	/* positive == non-fatal error */
>  	}
>  
> -	oldnode = find_existing_node(fabric, &node_buf);
> +	oldnode = find_existing_node(fabric, node_buf.guid);
>  	if (oldnode)
>  		remotenode = oldnode;
>  	else if (!(remotenode = create_node(fabric, scan, &node_buf, path,
> -- 
> 1.5.4.5
> 


-- 
Ira Weiny
Math Programmer/Computer Scientist
Lawrence Livermore National Lab
925-423-8008
weiny2-i2BcT+NCU+M@public.gmane.org
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