linux-kernel - Re: [PATCH 3/4] ALSA: timer: Introduce virtual userspace-driven timers

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Message-ID: <b9ac0ee3-18af-459d-958e-3b8122e7bb9d@gmail.com>
Date: Sun, 28 Jul 2024 12:54:55 +0100
From: Ivan Orlov <ivan.orlov0322@...il.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>, perex@...ex.cz,
 tiwai@...e.com, corbet@....net, broonie@...nel.org, shuah@...nel.org
Cc: linux-kselftest@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-sound@...r.kernel.org, linux-kernel@...r.kernel.org, aholzinger@....de
Subject: Re: [PATCH 3/4] ALSA: timer: Introduce virtual userspace-driven
 timers

On 7/28/24 11:29, Christophe JAILLET wrote:
> 
> I may be wrong but I think that ida allocates hunks for 1024 bits (128 
> bytes * 8) at a time. (see [1])
> 
> So with this extra sape and the sapce for the xarray, it would waste a 
> few bytes of memory, yes.
> 
> With ida, there is also some locking that may be unnecessary (but harmless)
> 
> 
> Hoping, I got it right, here are a few numbers:
> 
> On a x86_64, with allmodconfig:
> 
> Your initial patch:
>     text       data        bss        dec        hex    filename
>    55020       1783        268      57071       deef    sound/core/timer.o
> 
> With ida:
>    54763       1631        116      56510       dcbe    sound/core/timer.o
> + 128 bytes of runtime memory allocation
> 
> With bitmap:
>    54805       1535        132      56472       dc98    sound/core/timer.o
> 
> 
> I think that the code would be slightly more elegant with ida, but 
> implementing it with a bitmap does not add that much complexity.
> 

Ah, alright, I agree that the code would be cleaner when using IDA, and 
such a small memory overhead won't be significant/noticeable. I'm going 
to use IDA in the V2 instead of bitmap API, thank you so much for 
pointing me to it (I was wondering if the Kernel has a generic ID 
allocator and now I finally know it does :) ).

Thank you!

-- 
Kind regards,
Ivan Orlov