[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH] arm/irq: Reduce size of irq_desc array to exclude local IRQs
- To: Mykola Kvach <xakep.amatop@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: "Orzel, Michal" <michal.orzel@xxxxxxx>
- Date: Thu, 10 Apr 2025 09:25:19 +0200
- Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none
- Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=fMYTeH1/HV9XnW+AM2SSXm/F6djSjySFeTaO2Dx7NGQ=; b=sS/glz1A1EnEA9nUUIL7Ccq/xXHDYO7rTpjy/5UReNchcCDQbTchXy3xgvN4SwvtZ7eX/ZTYGhE3+N8X8gjiJhintnMnjd/HK8b2IJjDPfE4hqkvgVaxrFq52/NDpTSU/RM/c1/evsXIvsl7INunAJ6h6/s42cjSpvHvXHG0mGTvznpUU0fj6kROpk0i+V+abajzd9oGjkg/o+1LQi7m46jomPPvWgFhHH6IGkcA5lB2nRV/apMYc0p6nVh2WKP7I9l+U/+hoVGpWMt/a0Kg4iGx5ruk2x8jW06jwav2o8MdF/Tqhk9EOXndCZcBfKVDVMuRKHmHUvwdOgC5g4L4aA==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=qqflodGbQxH/hJLCA+6h59A9qKd92IEykBW+HCj2U/TS70UbiabMSty62gr5JwSzTsZi0dnJ7ZojzA2iMk+8lB7/nwa/lLaicgeuGFzjmRs6MOPNFtD+f8QvK3AWnHoggAEhzcXEBBHnxmvMy+N8PyPcod2qY6RNzY1owcv8pyHsV3l0PJfzb1F3c85vzw7kZTqHfazcwutVA5ZA++vhgRHXb8Hhy30q+o1i70GNj7Fi+D1ZHUuHclfMaivmePbeFyOc2BfIDlAp1/u2udrbcYOC/Dry43ajWsIgJF3mTA+ICj/G2LesIwcNEVCx+FKp8Jzp5LBUNDtaMznXHufLgg==
- Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com;
- Cc: Mykola Kvach <mykola_kvach@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Thu, 10 Apr 2025 07:25:49 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 08/04/2025 05:42, Mykola Kvach wrote:
>
>
> From: Mykola Kvach <mykola_kvach@xxxxxxxx>
>
> SGI and PPI descriptors are banked and stored in the per-CPU local_irq_desc
> array, so not all elements of the global irq_desc array are used. This is
> already accounted for in the descriptor lookup logic inside __irq_to_desc:
> return &irq_desc[irq - NR_LOCAL_IRQS];
>
> Therefore, the size of the irq_desc array can be reduced by NR_LOCAL_IRQS,
> saving (NR_LOCAL_IRQS * L1_CACHE_BYTES) bytes of memory.
Good finding. History shows that local_irq_desc was introduced after irq_desc
that could explain the mistake.
>
> Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
~Michal
|
