Hi Sage,
We are seeing the following mapper_lock is heavily contended and commenting out this lock is improving performance ~10 % (in the short circuit path).
This is called for every io from osd_is_valid_op_target().
I looked into the code ,but, couldn't understand the purpose of the lock , it seems redundant to me , could you please confirm ?
void do_rule(int rule, int x, vector<int>& out, int maxout,
const vector<__u32>& weight) const {
Mutex::Locker l(mapper_lock);
int rawout[maxout];
int scratch[maxout * 3];
int numrep = crush_do_rule(crush, rule, x, rawout, maxout, &weight[0], weight.size(), scratch);
if (numrep < 0)
numrep = 0;
out.resize(numrep);
for (int i=0; i<numrep; i++)
out[i] = rawout[i];
}
Thanks & Regards
Somnath
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