It was on there for a couple of months, and I didn't bother committing it until now. Nate signed off on it and we talked about it so I'm pretty sure it's correct.
The issue is that before we we're summing the operations (whatever they may be) instead of summing the vectors to do the operation. The best example is to figure out the total miss rate given that I've got a separate icache and dcache miss rate. Nominally the formula is miss_rate[] = misses[]/accesses[] Lets say I've got the following: Misses[inst] = 10 Accesses[inst] = 10000000 Misses[data] = 2000000 Accesses[data] = 10000000 The miss_rats::inst is 10/10000000 = 1e-06 and miss_rate::data is 2000000/10000000 = 0.20. With the old formula the miss_rate::total statistic would be 0.2000001. In reality it should be 0.1000001 because the component arrays should be added before the operation (divide) is applied to them. Thanks, Ali On 6/5/12 9:54 AM, "Steve Reinhardt" <[email protected]> wrote: >I missed seeing this on reviewboard. Can you provide an example of where >this was giving the wrong results? > >I'm concerned that perhaps saying X/Y for vector values of X and Y is just >ambiguous, and changing the definition like this may make it match one >person's expectations in one place while also breaking someone else's >expectations somewhere else. > >Or maybe I'm just confused by the comment... I see this fix is only in the >total() operation, but that's not mentioned in the description. > >Steve > >On Mon, Jun 4, 2012 at 10:24 PM, William Wang <[email protected]> >wrote: > >> changeset 4c0f7e5ae72a in /z/repo/gem5 >> details: http://repo.gem5.org/gem5?cmd=changeset;node=4c0f7e5ae72a >> description: >> stats: when applying an operation to two vectors sum the >>components >> first. >> >> Previously writing X/Y in a formula would result in: >> x[0]/y[0] + x[1]/y[1] >> In reality you want: >> (x[0] +x[1])/(y[0] + y[1]) >> >> diffstat: >> >> src/base/statistics.hh | 24 +++++++++++++++++++++++- >> 1 files changed, 23 insertions(+), 1 deletions(-) >> >> diffs (36 lines): >> >> diff -r 9cad1c26c3b3 -r 4c0f7e5ae72a src/base/statistics.hh >> --- a/src/base/statistics.hh Tue Jun 05 01:23:11 2012 -0400 >> +++ b/src/base/statistics.hh Tue Jun 05 01:23:11 2012 -0400 >> @@ -2289,9 +2289,31 @@ >> total() const >> { >> const VResult &vec = this->result(); >> + const VResult &lvec = l->result(); >> + const VResult &rvec = r->result(); >> Result total = 0.0; >> - for (off_type i = 0; i < size(); i++) >> + Result lsum = 0.0; >> + Result rsum = 0.0; >> + Op op; >> + >> + assert(lvec.size() > 0 && rvec.size() > 0); >> + assert(lvec.size() == rvec.size() || >> + lvec.size() == 1 || rvec.size() == 1); >> + >> + /** If vectors are the same divide their sums (x0+x1)/(y0+y1) >>*/ >> + if (lvec.size() == rvec.size() && lvec.size() > 1) { >> + for (off_type i = 0; i < size(); ++i) { >> + lsum += lvec[i]; >> + rsum += rvec[i]; >> + } >> + return op(lsum, rsum); >> + } >> + >> + /** Otherwise divide each item by the divisor */ >> + for (off_type i = 0; i < size(); ++i) { >> total += vec[i]; >> + } >> + >> return total; >> } >> >> _______________________________________________ >> gem5-dev mailing list >> [email protected] >> http://m5sim.org/mailman/listinfo/gem5-dev >> >_______________________________________________ >gem5-dev mailing list >[email protected] >http://m5sim.org/mailman/listinfo/gem5-dev > -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. _______________________________________________ gem5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/gem5-dev
