linux-kernel - Re: [PATCH 0/2] Limit number of hw queues by nr_cpu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Wed, 10 Apr 2019 08:18:50 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Dongli Zhang <dongli.zhang@...cle.com>, linux-scsi@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-block@...r.kernel.org
Cc:     mst@...hat.com, jasowang@...hat.com, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, cohuck@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] Limit number of hw queues by nr_cpu_ids for
 virtio-blk and virtio-scsi

On 3/27/19 4:36 AM, Dongli Zhang wrote:
> When tag_set->nr_maps is 1, the block layer limits the number of hw queues
> by nr_cpu_ids. No matter how many hw queues are use by
> virtio-blk/virtio-scsi, as they both have (tag_set->nr_maps == 1), they
> can use at most nr_cpu_ids hw queues.
> 
> In addition, specifically for pci scenario, when the 'num-queues' specified
> by qemu is more than maxcpus, virtio-blk/virtio-scsi would not be able to
> allocate more than maxcpus vectors in order to have a vector for each
> queue. As a result, they fall back into MSI-X with one vector for config
> and one shared for queues.
> 
> Considering above reasons, this patch set limits the number of hw queues
> used by nr_cpu_ids for both virtio-blk and virtio-scsi.

I picked both up for 5.1.

-- 
Jens Axboe