From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-6591-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id E91189841DA for ; Sun, 5 Jan 2020 11:26:07 +0000 (UTC) Date: Sun, 5 Jan 2020 06:25:59 -0500 From: "Michael S. Tsirkin" Message-ID: <20200105062023-mutt-send-email-mst@kernel.org> References: <85eeab19-1f53-6c45-95a2-44c1cfd39184@redhat.com> <28da67db-73ab-f772-fb00-5a471b746fc5@linux.intel.com> <683cac51-853d-c8c8-24c6-b01886978ca4@redhat.com> <42346d41-b758-967a-30b7-95aa0d383beb@linux.intel.com> <0c3d33de-3940-7895-2fe2-81de8714139c@redhat.com> <46806720-1D1C-40C3-BEE2-EDB0D4DA39BF@linux.alibaba.com> <7e151886-408e-2c1d-3958-77c26b8a4ac0@redhat.com> MIME-Version: 1.0 In-Reply-To: <7e151886-408e-2c1d-3958-77c26b8a4ac0@redhat.com> Subject: Re: [virtio-dev] Re: [PATCH v1 2/2] virtio-mmio: add features for virtio-mmio specification version 3 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline To: Jason Wang Cc: "Liu, Jiang" , "Liu, Jing2" , Zha Bin , linux-kernel@vger.kernel.org, slp@redhat.com, virtio-dev@lists.oasis-open.org, jing2.liu@intel.com, chao.p.peng@intel.com List-ID: On Fri, Jan 03, 2020 at 05:12:38PM +0800, Jason Wang wrote: >=20 > On 2020/1/3 =E4=B8=8B=E5=8D=882:14, Liu, Jiang wrote: > > > Ok, I get you now. > > >=20 > > > But still, having fixed number of MSIs is less flexible. E.g: > > >=20 > > > - for x86, processor can only deal with about 250 interrupt vectors. > > > - driver may choose to share MSI vectors [1] (which is not merged but= we will for sure need it) > > Thanks for the info:) > > X86 systems roughly have NCPU * 200 vectors available for device interr= upts. > > The proposed patch tries to map multiple event sources to an interrupt = vector, to avoid running out of x86 CPU vectors. > > Many virtio mmio devices may have several or tens of event sources, and= it=E2=80=99s rare to have hundreds of event sources. > > So could we treat the dynamic mapping between event sources and interru= pt vectors as an advanced optional feature? > >=20 >=20 > Maybe, but I still prefer to implement it if it is not too complex. Let's > see Michael's opinion on this. >=20 > Thanks I think a way for the device to limit # of vectors in use by driver is useful. But sharing of vectors doesn't really need any special registers, just program the same vector for multiple Qs/interrupts. --=20 MST --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org