> On Apr 20, 2022, at 7:42 AM, Song Liu wrote: > > Hi Linus, > >> On Apr 19, 2022, at 7:18 PM, Linus Torvalds wrote: >> >> On Tue, Apr 19, 2022 at 7:03 PM Alexei Starovoitov >> wrote: >>> >>> Here is the quote from Song's cover letter for bpf_prog_pack series: >> >> I care about performance as much as the next person, but I care about >> correctness too. >> >> That large-page code was a disaster, and was buggy and broken. >> >> And even with those four patches, it's still broken. >> >> End result: there's no way that thigh gets re-enabled without the >> correctness being in place. >> >> At a minimum, to re-enable it, it needs (a) that zeroing and (b) >> actual numbers on real loads. (not some artificial benchmark). >> >> Because without (a) there's no way in hell I'll enable it. >> >> And without (b), "performance" isn't actually an argument. > > I will send patch to do (a) later this week. > > For (b), we have seen direct map fragmentation causing visible > performance drop for our major services. This is the shadow > production benchmark, so it is not possible to run it out of > our data centers. Tracing showed that BPF program was the top > trigger of these direct map splits. Attached is the patch for (a). I also sent it to the mail list. Thanks, Song