[SCSI] fcoe: Round-robin based selection of CPU for post-processing of incoming commands
Problem: Earlier mechanism of selection of CPU was, to select the same CPU which has received incoming request. Hence in case of rx_id = 0xFFFF, request was always posted to same NetRx queue, hence only 1 CPU is utilized for handling the command. It was also causing problem of "running out of exchanges from per CPU pool of exchanges (in case of DDP offload) Fix: Implemented new algo. to select CPU for post-processing of incoming commands when rx_id is unknown. This is simple Round robin algo. for CPU selection. Notes/Dependencies: N/A Signed-off-by: Kiran Patil <kiran.patil@intel.com> Signed-off-by: Robert Love <robert.w.love@intel.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
parent
1ff9918b62
commit
064287eee3
|
@ -1244,6 +1244,36 @@ static int fcoe_cpu_callback(struct notifier_block *nfb,
|
|||
return NOTIFY_OK;
|
||||
}
|
||||
|
||||
/**
|
||||
* fcoe_select_cpu() - Selects CPU to handle post-processing of incoming
|
||||
* command.
|
||||
* @curr_cpu: CPU which received request
|
||||
*
|
||||
* This routine selects next CPU based on cpumask.
|
||||
*
|
||||
* Returns: int (CPU number). Caller to verify if returned CPU is online or not.
|
||||
*/
|
||||
static unsigned int fcoe_select_cpu(unsigned int curr_cpu)
|
||||
{
|
||||
static unsigned int selected_cpu;
|
||||
|
||||
if (num_online_cpus() == 1)
|
||||
return curr_cpu;
|
||||
/*
|
||||
* Doing following check, to skip "curr_cpu (smp_processor_id)"
|
||||
* from selection of CPU is intentional. This is to avoid same CPU
|
||||
* doing post-processing of command. "curr_cpu" to just receive
|
||||
* incoming request in case where rx_id is UNKNOWN and all other
|
||||
* CPU to actually process the command(s)
|
||||
*/
|
||||
do {
|
||||
selected_cpu = cpumask_next(selected_cpu, cpu_online_mask);
|
||||
if (selected_cpu >= nr_cpu_ids)
|
||||
selected_cpu = cpumask_first(cpu_online_mask);
|
||||
} while (selected_cpu == curr_cpu);
|
||||
return selected_cpu;
|
||||
}
|
||||
|
||||
/**
|
||||
* fcoe_rcv() - Receive packets from a net device
|
||||
* @skb: The received packet
|
||||
|
@ -1320,9 +1350,16 @@ int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
|
|||
*/
|
||||
if (ntoh24(fh->fh_f_ctl) & FC_FC_EX_CTX)
|
||||
cpu = ntohs(fh->fh_ox_id) & fc_cpu_mask;
|
||||
else
|
||||
else {
|
||||
cpu = smp_processor_id();
|
||||
|
||||
if ((fh->fh_type == FC_TYPE_FCP) &&
|
||||
(ntohs(fh->fh_rx_id) == FC_XID_UNKNOWN)) {
|
||||
do {
|
||||
cpu = fcoe_select_cpu(cpu);
|
||||
} while (!cpu_online(cpu));
|
||||
}
|
||||
}
|
||||
fps = &per_cpu(fcoe_percpu, cpu);
|
||||
spin_lock_bh(&fps->fcoe_rx_list.lock);
|
||||
if (unlikely(!fps->thread)) {
|
||||
|
|
Loading…
Reference in a new issue