ref: cf8ff0e71369afdf600e36924c2d046ecf783cbf
parent: 5fd2e746e1a2a00d2acbc0c3b1924b1ea22101e8
author: cinap_lenrek <[email protected]>
date: Sat Oct 17 22:51:32 EDT 2020
sdnvme: handle machines with more cpu's than submit queues (thanks mischief) We used to assume a 1:1 pairing of processors to submit queues. With recent machines, we now got more cpu cores than what some nvme drives support so we need to distribute the queues across these cpu's which requires locking on command submission. There is a feature get/set command to probe the number of submit and completion queues, but we decided to just handling submission queue create command error gracefully as it is simpler and has less chance of regression with existing setups. Thanks to mischief for investigating and writing the code.
--- a/sys/src/9/pc/sdnvme.c
+++ b/sys/src/9/pc/sdnvme.c
@@ -41,6 +41,7 @@
u32int *base;
WS **wait;
Ctlr *ctlr;
+ Lock;
};
struct Ctlr
@@ -63,6 +64,8 @@
u32int mpsshift;
u32int dstrd;
+ u32int nsq;
+
CQ cq[1+1];
SQ sq[1+MAXMACH];
@@ -99,7 +102,9 @@
if(!adm){
Retry:
splhi();
- sq = &ctlr->sq[1+m->machno];
+ sq = &ctlr->sq[1+(m->machno % ctlr->nsq)];
+ if(conf.nmach > ctlr->nsq)
+ lock(sq);
} else {
qlock(ctlr);
sq = &ctlr->sq[0];
@@ -207,7 +212,9 @@
coherence();
ctlr->reg[DBell + ((sq-ctlr->sq)*2+0 << ctlr->dstrd)] = sq->tail & sq->mask;
if(sq > ctlr->sq) {
- assert(sq == &ctlr->sq[1+m->machno]);
+ assert(sq == &ctlr->sq[1+(m->machno % ctlr->nsq)]);
+ if(conf.nmach > ctlr->nsq)
+ unlock(sq);
spllo();
} else
qunlock(sq->ctlr);
@@ -381,7 +388,7 @@
static void
setupqueues(Ctlr *ctlr)
{
- u32int lgsize, *e;
+ u32int lgsize, st, *e;
CQ *cq;
SQ *sq;
WS ws;
@@ -400,6 +407,8 @@
e[11] = 3; /* IEN | PC */
checkstatus(wcmd(&ws), "create completion queue");
+ st = 0;
+
/* SQID[1..nmach]: submission queue per cpu */
for(i=1; i<=conf.nmach; i++){
sq = &ctlr->sq[i];
@@ -407,8 +416,19 @@
e = qcmd(&ws, ctlr, 1, 0x01, 0, nil, sq->base, 0x1000);
e[10] = i | sq->mask<<16;
e[11] = (cq - ctlr->cq)<<16 | 1; /* CQID<<16 | PC */
- checkstatus(wcmd(&ws), "create submission queue");
+
+ st = wcmd(&ws);
+ if(st != 0){
+ free(sq->base);
+ free(sq->wait);
+ memset(sq, 0, sizeof(*sq));
+ break;
+ }
}
+
+ ctlr->nsq = i - 1;
+ if(ctlr->nsq < 1)
+ checkstatus(st, "create submission queues");
ilock(&ctlr->intr);
ctlr->ints |= 1<<(cq - ctlr->cq);
@@ -544,7 +564,7 @@
Ready:
identify(ctlr);
setupqueues(ctlr);
-
+ print("%s: using %d submit queues\n", name, ctlr->nsq);
poperror();
return 1;