>For credit purposes, the standard is peak FLOPS, >i.e. we give credit for what the device could do, >rather than what it actually did. >Among other things, this encourages projects to develop more efficient apps.
It does the opposite because many projects care more about attracting volunteers than they do about efficient computation. First: Per second of run time, a host gets the same credit for a non-optimized stock app as it does for an optimized stock app. There's no benefit to the volunteer to go to a project with optimized apps. In fact there's a benefit for users to compile an optimized app for use at a non-optimized project where their credit will be higher. Every time we optimize SETI@home we get bombarded by users of non-stock optimized apps get angry because their RAC goes down. That makes it a disincentive to optimize. Second: This method encourages projects to create separate apps for GPUs rather than separate app_versions. Because GPUs obtain nowhere near their advertised rates for real code, a separate GPU app can earn 20 to 100x the credit of a GPU app_version of an app that also has CPU app_versions. Third: It encourages projects to not use the BOINC credit granting mechanisms. To compete with projects that have GPU only apps, some projects grant outrageous credit for everything. On Tue, Jun 10, 2014 at 11:34 AM, David Anderson <[email protected]> wrote: > For credit purposes, the standard is peak FLOPS, > i.e. we give credit for what the device could do, > rather than what it actually did. > Among other things, this encourages projects to develop more efficient > apps. > > Currently we're not measuring this well for x86 CPUs, > since our Whetstone benchmark isn't optimized. > Ideally the BOINC client should include variants for the most common > CPU features, as we do for ARM. > > -- D > > > On 10-Jun-2014 2:09 AM, Richard Haselgrove wrote: > >> Before anybody leaps into making any changes on the basis of that >> observation, I >> think we ought to pause and consider why we have a benchmark, and what we >> use it for. >> >> I'd suggest that in an ideal world, we would be measuring the actual >> running speed >> of (each project's) science applications on that particular host, >> optimisations and >> all. We gradually do this through the runtime averages anyway, but it's >> hard to >> gather a priori data on a new host. >> >> Instead of (initially) measuring science application performance, we >> measure >> hardware performance as a surrogate. We now have (at least) three ways of >> doing that: >> >> x86: minimum, most conservative, estimate, no optimisations allowed for. >> Android: allows for optimised hardware pathways with vfp or neon, but >> doesn't relate >> back to science app capability. >> GPU: maximum theoretical 'peak flops', calculated from card parameters, >> then scaled >> back by rule of thumb. >> >> Maybe we should standardise on just one standard? >> >> ------------------------------------------------------------ >> ------------------------ >> *From:* Richard Haselgrove <[email protected]> >> *To:* Josef W. Segur <[email protected]>; David Anderson >> <[email protected]> >> *Cc:* "[email protected]" <[email protected]> >> *Sent:* Tuesday, 10 June 2014, 9:37 >> *Subject:* Re: [boinc_dev] EXIT_TIME_LIMIT_EXCEEDED (sorry, yes me >> again, but >> >> please read) >> >> http://boinc.berkeley.edu/gitweb/?p=boinc-v2.git;a=commit;h= >> 7b2ca9e787a204f2a57f390bc7249bb7f9997fea >> >> >________________________________ >> > From: Josef W. Segur <[email protected] <mailto: >> [email protected]>> >> >To: David Anderson <[email protected] <mailto: >> [email protected]>> >> >Cc: "[email protected] <mailto:[email protected] >> >" >> <[email protected] <mailto:[email protected]>>; >> Eric J Korpela >> <[email protected] <mailto:[email protected]>>; >> Richard Haselgrove >> <[email protected] <mailto:[email protected]>> >> >> >Sent: Tuesday, 10 June 2014, 2:19 >> >Subject: Re: [boinc_dev] EXIT_TIME_LIMIT_EXCEEDED (sorry, yes me >> again, but >> please read) >> > >> > >> >Consider Richard's observation: >> > >> >>> It appears that the Android Whetstone benchmark used in the >> BOINC >> client has >> >>> separate code paths for ARM, vfp, and NEON processors: a vfp >> or NEON >> processor >> >>> will report that it is significantly faster than a >> plain-vanilla ARM. >> > >> >If that is so, it distinctly differs from the x86 Whetstone which >> never uses >> SIMD, and is truly conservative as you would want for 3). >> >-- >> > Joe >> > >> > >> > >> >On Mon, 09 Jun 2014 16:43:17 -0400, David Anderson < >> [email protected] >> <mailto:[email protected]>> wrote: >> > >> >> Eric: >> >> >> >> Yes, I suspect that's what's going on. >> >> Currently the logic for estimating job runtime >> >> (estimate_flops() in sched_version.cpp) is >> >> 1) if this (host, app version) has > 10 results, use (host, app >> version) >> statistics >> >> 2) if this app version has > 100 results, use app version >> statistics >> >> 3) else use a conservative estimate based on p_fpops. >> >> >> >> I'm not sure we should be doing 2) at all, >> >> since as you point out the first x100 or 1000 results for an app >> version >> >> will generally be from the fastest devices >> >> (and even in the steady state, >> >> app version statistics disproportionately reflect fast devices). >> >> >> >> I'll make this change. >> >> >> >> -- David >> >> >> >> On 09-Jun-2014 8:10 AM, Eric J Korpela wrote: >> >>> I also don't have direct access to the server as well, so I'm >> mostly guessing. >> >>> Having separate benchmarks for neon and VFP means there's a >> broad bimodal >> >>> distribution for the benchmark results. Where the mean falls >> depends upon >> the mix >> >>> of machines. In general the neon machines (being newer and >> faster) will report >> >>> first and more often, so early on the PFC distribution will >> reflect the fast >> >>> machines. Slower machines will be underweighted. So the work >> will be >> estimated to >> >>> complete quickly, and some machines will time out. In SETI >> beta, it >> resolves itself >> >>> in a few weeks. I can't guarantee that it will anywhere else. >> >>> >> >>> We see this with every release of a GPU app. The real >> capabilities of graphics >> >>> cards vary by orders of magnitude from the estimate and by more >> from each >> other. >> >>> The fast cards report first and most every else hits days of >> timeouts. >> >>> >> >>> One possible fix so to increase the timeout limits for the first >> 10 >> workunits for a >> >>> host_app_version, until host based estimates take over. >> >>> >> >>> >> >>> >> >>> >> >>> On Mon, Jun 9, 2014 at 2:02 AM, Richard Haselgrove >> <[email protected] <mailto:[email protected]> >> >>> <mailto:[email protected] >> >> <mailto:[email protected]>>> wrote: >> >>> >> >>> I think Eric Korpela would be the best person to answer that >> question, >> but I >> >>> suspect 'probably not': further investigation over the >> weekend suggests >> that the >> >>> circumstances may be SIMAP-specific. >> >>> >> >>> It appears that the Android Whetstone benchmark used in the >> BOINC >> client has >> >>> separate code paths for ARM, vfp, and NEON processors: a vfp >> or NEON >> processor >> >>> will report that it is significantly faster than a >> plain-vanilla ARM. >> >>> >> >>> However, SIMAP have only deployed a single Android app, >> which I'm >> assuming only >> >>> uses ARM functions: devices with vfp or NEON SIMD >> vectorisation >> available would >> >>> run the non-optimised application much slower than BOINC >> expects. >> >>> >> >>> At my suggestion, Thomas Rattei (SIMAP admistrator) >> increased the >> >>> rsc_fpops_bound multiplier to 10x on Sunday afternoon. I >> note that the >> maximum >> >>> runtime displayed on http://boincsimap.org/ >> boincsimap/server_status.php has >> >>> already increased from 11 hours to 14 hours since he did >> that. >> >>> >> >>> Thomas has told me "We've seen that >> [EXIT_TIME_LIMIT_EXCEEDED] a lot. >> However, >> >>> due to Samsung PowerSleep, we thought these are mainly >> "lazy" users >> just not >> >>> using their phone regularly for computing." He's going to >> monitor how this >> >>> progresses during the remainder of the current batch, and >> I've asked >> him to keep >> >>> us updated on his observations. >> >>> >> >>> >> >>> >> >>> >________________________________ >> >>> > From: David Anderson <[email protected] >> <mailto:[email protected]> <mailto:[email protected] >> >> <mailto:[email protected]>>> >> >>> >To: [email protected] <mailto:boinc_dev@ssl. >> berkeley.edu> >> <mailto:[email protected] <mailto:boinc_dev@ssl. >> berkeley.edu>> >> >> >>> >Sent: Monday, 9 June 2014, 3:48 >> >>> >Subject: Re: [boinc_dev] EXIT_TIME_LIMIT_EXCEEDED (sorry, >> yes me >> again, but >> >>> please read) >> >>> > >> >>> > >> >>> >Does this problem occur on SETI@home? >> >>> >-- David >> >>> > >> >>> >On 07-Jun-2014 2:51 AM, Richard Haselgrove wrote: >> >>> > >> >>> >> 2) Android runtime estimates >> >>> >> >> >>> >> The example here is from SIMAP. During a recent pause >> between >> batches, I noticed >> >>> >> that some of my 'pending validation' tasks were being >> slow to clear: >> >>> >> http://boincsimap.org/boincsimap/results.php?hostid= >> 349248 >> >>> >> >> >>> >> The clearest example is the third of those three >> workunits: >> >>> >> http://boincsimap.org/boincsimap/workunit.php?wuid= >> 57169928 >> >>> >> >> >>> >> Four of the seven replications have failed with 'Error >> while >> computing', and >> >>> >> every one of those four is an EXIT_TIME_LIMIT_EXCEEDED >> on an >> Android device. >> >>> >> >> >>> >> Three of the four hosts have never returned a valid >> result (total >> credit zero), >> >>> >> so they have never had a chance to establish an APR for >> use in runtime >> >>> >> estimation: runtime estimates and bounds must have been >> generated >> by the server. >> >>> >> >> >>> >> It seems - from these results, and others I've found >> pending on >> other machines - >> >>> >> that SIMAP tasks on Android are aborted with >> EXIT_TIME_LIMIT_EXCEEDED after ~6 >> >>> >> hours elapsed. For the new batch released today, SIMAP >> are using a >> 3x bound >> >>> >> (which may be a bit low under the circumstances): >> >>> >> >> >>> >> <rsc_fpops_est>13500000000000.000000</rsc_fpops_est> >> >>> >> <rsc_fpops_bound>40500000000000.000000</rsc_fpops_bound> >> >>> >> >> >>> >> so I deduce that the tasks when first issued had a >> runtime estimate >> of ~2 hours. >> >>> >> >> >>> >> My own tasks, on a fast Intel i5 'Haswell' CPU (APR 7.34 >> GFLOPS), >> take over half >> >>> >> an hour to complete: two hours for an ARM device sounds >> suspiciously low. The >> >>> >> only one of my Android wingmates to have registered an >> APR >> >>> >> >> (http://boincsimap.org/boincsimap/host_app_versions.php?hostid=771033) >> is >> >>> showing >> >>> >> 1.69 GFLOPS, but I have no way of knowing whether that >> APR was >> established >> >>> before >> >>> >> or after the task in question errored out. >> >>> >> >> >>> >> From experience - borne out by current tests at >> Albert@Home, where >> server logs >> >>> >> are helpfully exposed to the public - initial server >> estimates can >> be hopelessly >> >>> >> over-optimistic. These two are for the same machine: >> >>> >> >> >>> >> 2014-06-04 20:28:09.8459 [PID=26529] [version] [AV#716] >> (BRP4G-cuda32-nv301) >> >>> >> adjusting projected flops based on PFC avg: 2124.60G >> 2014-06-07 >> 09:30:56.1506 >> >>> >> [PID=10808] [version] [AV#716] (BRP4G-cuda32-nv301) >> setting >> projected flops >> >>> based >> >>> >> on host elapsed time avg: 23.71G >> >>> >> >> >>> >> Since SIMAP have recently announced that they are >> leaving the BOINC >> platform at >> >>> >> the end of the year (despite being an Android launch >> partner with >> Samsung), I >> >>> >> doubt they'll want to put much effort into researching >> this issue. >> >>> >> >> >>> >> But if other projects experimenting with Android >> applications are >> experiencing a >> >>> >> high task failure rate, they might like to check whether >> >>> EXIT_TIME_LIMIT_EXCEEDED >> >>> >> is a significant factor in those failures, and if so, >> consider the >> other >> >>> >> remediation approaches (apart from outliers, which isn't >> relevant >> in this case) >> >>> >> that I suggested to Eric Mcintosh at LHC. >> > >> > >> > >> _______________________________________________ >> boinc_dev mailing list >> [email protected] <mailto:[email protected]> >> >> http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev >> To unsubscribe, visit the above URL and >> (near bottom of page) enter your email address. >> >> >> _______________________________________________ > boinc_dev mailing list > [email protected] > http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev > To unsubscribe, visit the above URL and > (near bottom of page) enter your email address. > _______________________________________________ boinc_dev mailing list [email protected] http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev To unsubscribe, visit the above URL and (near bottom of page) enter your email address.
