linux-kernel - Re: [PATCH v4 00/10] kunit: Add dynamically-extending log

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Date:   Tue, 15 Aug 2023 17:18:54 +0800
From:   David Gow <davidgow@...gle.com>
To:     Richard Fitzgerald <rf@...nsource.cirrus.com>
Cc:     brendan.higgins@...ux.dev, rmoar@...gle.com,
        linux-kselftest@...r.kernel.org, kunit-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, patches@...nsource.cirrus.com
Subject: Re: [PATCH v4 00/10] kunit: Add dynamically-extending log

On Mon, 14 Aug 2023 at 21:23, Richard Fitzgerald
<rf@...nsource.cirrus.com> wrote:
>
> This patch chain changes the logging implementation to use string_stream
> so that the log will grow dynamically.
>
> The first 8 patches add test code for string_stream, and make some
> changes to string_stream needed to be able to use it for the log.
>
> The final patch adds a performance report of string_stream.
>
> CHANGES SINCE V3:
>
> Completely rewritten to use string_stream instead of implementing a
> separate extending-buffer implementation for logging.
>
> I have used the performance test from the final patch on my original
> fixed-size-fragment implementation from V3 to get a comparison of the
> two implementations (run on i3-8145UE CPU @ 2.20GHz):
>
>                         string_stream     V3 fixed-size-buffer
> Time elapsed:           7748 us           3251 us
> Total string length:    573890            573890
> Bytes requested:        823994            728336
> Actual bytes allocated: 1061440           728352
>
> I don't think the difference is enough to be worth complicating the
> string_stream implementation with my fixed-fragment implementation from
> V3 of this patch chain.
>

Thanks very much! I think this is good to go: I've added a few small
comments on various patches, but none of them are serious enough to
make me feel we _need_ a new version.
I'll leave it for a day or two in case there are any other comments or
any changes you want to make, otherwise this can be merged.

I agree the performance difference isn't worth the effort. If we
change our minds and want to change the implementation over later,
that shouldn't be a problem either. So let's stick with it as is.

Cheers,
-- David


> Richard Fitzgerald (10):
>   kunit: string-stream: Improve testing of string_stream
>   kunit: string-stream: Don't create a fragment for empty strings
>   kunit: string-stream: Add cases for adding empty strings to a
>     string_stream
>   kunit: string-stream: Add option to make all lines end with newline
>   kunit: string-stream: Add cases for string_stream newline appending
>   kunit: string-stream: Pass struct kunit to string_stream_get_string()
>   kunit: string-stream: Decouple string_stream from kunit
>   kunit: string-stream: Add test for freeing resource-managed
>     string_stream
>   kunit: Use string_stream for test log
>   kunit: string-stream: Test performance of string_stream
>
>  include/kunit/test.h           |  14 +-
>  lib/kunit/Makefile             |   5 +-
>  lib/kunit/debugfs.c            |  36 ++-
>  lib/kunit/kunit-test.c         |  52 +---
>  lib/kunit/log-test.c           |  72 ++++++
>  lib/kunit/string-stream-test.c | 447 +++++++++++++++++++++++++++++++--
>  lib/kunit/string-stream.c      | 129 +++++++---
>  lib/kunit/string-stream.h      |  22 +-
>  lib/kunit/test.c               |  48 +---
>  9 files changed, 656 insertions(+), 169 deletions(-)
>  create mode 100644 lib/kunit/log-test.c
>
> --
> 2.30.2
>

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