linux-kernel - Re: [PATCH 5/5] genirq: Use the maple tree for IRQ descriptors management

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Message-ID: <cfc3b77b-7e02-d5b7-382c-00cccc4e2914@nvidia.com>
Date:   Tue, 31 Jan 2023 10:45:38 -0600
From:   Shanker Donthineni <sdonthineni@...dia.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>, Michael Walle <michael@...le.cc>
Cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Hans de Goede <hdegoede@...hat.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] genirq: Use the maple tree for IRQ descriptors
 management



On 1/31/23 03:52, Thomas Gleixner wrote:
> External email: Use caution opening links or attachments
> 
> 
> On Sun, Jan 29 2023 at 18:57, Shanker Donthineni wrote:
>> The current implementation uses a static bitmap and a radix tree
>> to manage IRQ allocation and irq_desc pointer store respectively.
>> However, the size of the bitmap is constrained by the build time
>> macro MAX_SPARSE_IRQS, which may not be sufficient to support the
>> high-end servers, particularly those with GICv4.1 hardware, which
>> require a large interrupt space to cover LPIs and vSGIs
>>
>> The maple tree is a highly efficient data structure for storing
>> non-overlapping ranges and can handle a large number of entries,
>> up to ULONG_MAX. It can be utilized for both storing IRQD and
> 
> IRQD ??. Please write it out: interrupt descriptors
> 
> Changelogs have no space constraints and there is zero value to
> introduce unreadable acronyms.
> 
>>   static DEFINE_MUTEX(sparse_irq_lock);
>> -static DECLARE_BITMAP(allocated_irqs, MAX_SPARSE_IRQS);
>> +static struct maple_tree sparse_irqs = MTREE_INIT_EXT(sparse_irqs,
>> +                                     MT_FLAGS_ALLOC_RANGE |
>> +                                     MT_FLAGS_LOCK_EXTERN |
>> +                                     MT_FLAGS_USE_RCU, sparse_irq_lock);
> 
> Nit. Can we please format this properly:
> 
> static struct maple_tree sparse_irqs = MTREE_INIT_EXT(sparse_irqs,
>                                                        MT_FLAGS_ALLOC_RANGE |
>                                                        MT_FLAGS_LOCK_EXTERN |
>                                                        MT_FLAGS_USE_RCU,
>                                                        sparse_irq_lock);
> 
> Other than that this looks really good.
> 

I'll update in v2 patch.

Thanks,
Shanker