________________________________________ From: Martin K. Petersen Sent: Wednesday, February 12, 2025 6:56 PM To: Sagar Biradar - C34249 Cc: linux-scsi@xxxxxxxxxxxxxxx; Tomas Henzl; Marco Patalano; Scott Benesh - C33703; Don Brace - C33706; Tom White - C33503; Abhinav Kuchibhotla - C70322 Subject: Re: [PATCH] [v2]aacraid: Reply queue mapping to CPUs based on IRQ affinity [You don't often get email from "martin.petersen@oracle.comjames.bottomley@hansenpartnership.comjmeneghi"@redhat.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ;] EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe Hi Sagar! > Add a new modparam "aac_cpu_offline_feature" to control CPU offlining. > By default, it's disabled (0), but can be enabled during driver load > with: > insmod ./aacraid.ko aac_cpu_offline_feature=1 We are very hesitant when it comes to adding new module parameters. And why wouldn't you want offlining to just work? Is the performance penalty really substantial enough that we have to introduce an explicit "don't be broken" option? Hi Martin, Thank you for your time to review and giving your valuable opinion. There are two reasons why I chose the modparam way 1) As you rightly guessed - the performance penalty is high when it comes to few RAID level configurations - which is not desired 2) Not a lot of people would use CPU offlining feature as part of their regular usage. This is mostly for admin purposes. These two reasons made me opt for the modparam. We and our folks at RedHat did venture into trying few other options - but this seemed like a nice fit. -- Martin K. Petersen Oracle Linux Engineering
