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Re: [PATCH v5 3/5] grub-mkconfig hurd: Fix quadratic algorithm for sorti


From: Mathieu Desnoyers
Subject: Re: [PATCH v5 3/5] grub-mkconfig hurd: Fix quadratic algorithm for sorting menu items
Date: Mon, 13 Jun 2022 10:02:27 -0400 (EDT)

----- On Jun 11, 2022, at 7:55 PM, samuel thibault samuel.thibault@ens-lyon.org 
wrote:

> Hello,
> 
> Mathieu Desnoyers, le jeu. 09 juin 2022 14:50:22 -0400, a ecrit:
>> The current implementation of the 10_hurd script implements its menu
>> items sorting in bash with a quadratic algorithm, calling "sed", "sort",
>> "head", and "grep" to compare versions between individual lines, which
>> is annoyingly slow for kernel developers who can easily end up with
>> 50-100 kernels in their boot partition.
>> 
>> This fix is ported from the 10_linux script, which has a similar
>> quadratic code pattern.
>> 
>> [ Note: this is untested. I would be grateful if anyone with a Hurd
>>   environment could test it before it is merged. ]
>> 
>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
>> Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
> 
> Tested-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

Noted. Adding your Tested-by tag to the message for my
next round. Thanks!

Mathieu

> 
>> ---
>> Changes since v4:
>> - Combine sed -e '...' -e '...' into sed -e '...; ...'
>> ---
>>  util/grub.d/10_hurd.in | 14 +++++++++-----
>>  1 file changed, 9 insertions(+), 5 deletions(-)
>> 
>> diff --git a/util/grub.d/10_hurd.in b/util/grub.d/10_hurd.in
>> index 2fafa4e59..4294bbe4c 100644
>> --- a/util/grub.d/10_hurd.in
>> +++ b/util/grub.d/10_hurd.in
>> @@ -197,11 +197,17 @@ title_correction_code=
>>  # Extra indentation to add to menu entries in a submenu. We're not in a 
>> submenu
>>  # yet, so it's empty. In a submenu it will be equal to '\t' (one tab).
>>  submenu_indentation=""
>> -is_top_level=true
>>  
>> -while [ "x$kernels" != "x" ] ; do
>> -  kernel=`version_find_latest $kernels`
>> +# Perform a reverse version sort on the entire kernels list.
>> +# Temporarily replace the '.old' suffix by ' 1' and append ' 2' for all
>> +# other files to order the '.old' files after their non-old counterpart
>> +# in reverse-sorted order.
>> +
>> +reverse_sorted_kernels=$(echo ${kernels} | tr ' ' '\n' | sed -e 's/\.old$/ 
>> 1/;
>> / 1$/! s/$/ 2/' | version_sort -r | sed -e 's/ 1$/.old/; s/ 2$//')
>>  
>> +is_top_level=true
>> +
>> +for kernel in ${reverse_sorted_kernels}; do
>>    # The GRUB_DISABLE_SUBMENU option used to be different than others since 
>> it was
>>    # mentioned in the documentation that has to be set to 'y' instead of 
>> 'true' to
>>    # enable it. This caused a lot of confusion to users that set the option 
>> to 'y',
>> @@ -221,8 +227,6 @@ while [ "x$kernels" != "x" ] ; do
>>  
>>    hurd_entry "$kernel" advanced
>>    hurd_entry "$kernel" recovery
>> -
>> -  kernels=`echo $kernels | tr ' ' '\n' | fgrep -vx "$kernel" | tr '\n' ' '`
>>  done
>>  
>>  # If at least one kernel was found, then we need to
>> --
>> 2.30.2
>> 
> 
> --
> Samuel
> ---
> Pour une évaluation indépendante, transparente et rigoureuse !
> Je soutiens la Commission d'Évaluation de l'Inria.

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com



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