From: Jens Axboe <axboe@kernel.dk>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Recent slowdown in single object builds
Date: Sat, 16 Nov 2019 09:57:06 -0700 [thread overview]
Message-ID: <8caa1edf-9c6f-15e4-218d-c266013f8e28@kernel.dk> (raw)
In-Reply-To: <CAK7LNATVHbMHqjboACJF8BbKianRfjiGhHTXjtQuJVmv2HFPUA@mail.gmail.com>
On 11/16/19 12:17 AM, Masahiro Yamada wrote:
> On Sat, Nov 16, 2019 at 8:10 AM Jens Axboe <axboe@kernel.dk> wrote:
>>
>> Hi,
>>
>> I've noticed that current -git is a lot slower at doing single object
>> builds than earlier kernels. Here's an example, building the exact same
>> file on 5.2 and -git:
>>
>> $ time make fs/io_uring.o
>> real 0m5.953s
>> user 0m5.402s
>> sys 0m0.649s
>>
>> vs 5.2 based (with all the backports, identical file):
>>
>> $ time make fs/io_uring.o
>> real 0m3.218s
>> user 0m2.968s
>> sys 0m0.520s
>>
>> Any idea what's going on here? It's almost twice as slow, which is
>> problematic...
>
>
>
> This is necessary cost
> to do single builds
> (394053f4a4b3e3eeeaa67b67fc886a9a75bd9e4d)
> but, it is much better in linux-next.
Very sad that it's now twice as slow as before, that's a real problem.
This isn't a marginal slowdown.
I've never had issues with single object builds before, and in fact
it's often useful to build stuff that's disabled as a single object.
Where's the report that led to this commit being necessary?
--
Jens Axboe
next prev parent reply other threads:[~2019-11-16 16:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-15 23:10 Recent slowdown in single object builds Jens Axboe
2019-11-16 7:17 ` Masahiro Yamada
2019-11-16 16:57 ` Jens Axboe [this message]
2019-11-18 0:40 ` Masahiro Yamada
2019-11-18 2:34 ` Jens Axboe
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