> On Apr 20, 2022, at 7:42 AM, Song Liu <songliubraving@xxxxxx> wrote:
>
> Hi Linus,
>
>> On Apr 19, 2022, at 7:18 PM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>
>> On Tue, Apr 19, 2022 at 7:03 PM Alexei Starovoitov
>> <alexei.starovoitov@xxxxxxxxx> 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
Attachment:
0001-bpf-invalidate-unused-part-of-bpf_prog_pack.patch
Description: 0001-bpf-invalidate-unused-part-of-bpf_prog_pack.patch
