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From Tim Armstrong <tarmstr...@cloudera.com>
Subject Re: impala query spend too much time on codegen
Date Fri, 25 Mar 2016 03:37:48 GMT
>From what I can tell Safari uses a four-tier JIT where at one end
interpreted code has no start-up time but slow runtime and at the other end
the full LLVM pipeline generates high-quality code but takes a long time to
start-up. In-between there are two intermediate stages where they use some
parts of LLVM. Currently in Impala we only really have two tiers
(interpreted and high-quality LLVM codegen), so we sometimes spend too much
time optimising code for short-running queries.

This was the page I found:
https://webkit.org/blog/3362/introducing-the-webkit-ftl-jit/ but maybe you
saw something more recent.

On Thu, Mar 24, 2016 at 8:31 PM, Tim Armstrong <tarmstrong@cloudera.com>
wrote:

> IMO even though LLVM is more heavyweight than a custom JIT, there is
> plenty of room to improve codegen time for shorter-running Impala queries
> given some engineering effort.
>
> On Thu, Mar 24, 2016 at 8:18 PM, 吴朱华 <ikewu83@gmail.com> wrote:
>
>> I can see that, apple safari team have just switch llvm to something
>> custom made on their new JS jit engine.
>>
>> 2016-03-25 10:35 GMT+08:00 Tim Armstrong <tarmstrong@cloudera.com>:
>>
>>> Oops, I meant Impala 2.6
>>>
>>> On Thu, Mar 24, 2016 at 8:26 AM, Tim Armstrong <tarmstrong@cloudera.com>
>>> wrote:
>>>
>>>> We'll be upgrading to LLVM 3.8 in Impala 2.7. I've been working on the
>>>> upgrade. It doesn't help with codegen time (actually it hurts) but there
>>>> are other benefits.
>>>>
>>>> Thanks,
>>>> Tim
>>>>
>>>> On Wed, Mar 23, 2016 at 10:51 PM, zhen <yyzzjj0515@gmail.com> wrote:
>>>>
>>>>> just now  impala use the  llvm  version is 3.3  that  api not
>>>>> compatible with  3.5 + .  cur  could not test
>>>>>
>>>>>
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>>>>
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>
>

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