From: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
To: "Hyong Youb Kim (hyonkim)" <hyonkim@cisco.com>,
Nithin Kumar Dabilpuram <ndabilpuram@marvell.com>,
David Marchand <david.marchand@redhat.com>,
"Thomas Monjalon" <thomas@monjalon.net>,
Ferruh Yigit <ferruh.yigit@intel.com>,
"Bruce Richardson" <bruce.richardson@intel.com>
Cc: "John Daley (johndale)" <johndale@cisco.com>,
Shahed Shaikh <shshaikh@marvell.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [RFC PATCH v3 2/3] eal: add mask and unmask interrupt APIs
Date: Wed, 17 Jul 2019 06:14:44 +0000 [thread overview]
Message-ID: <BYAPR18MB24245854682BF59031401A42C8C90@BYAPR18MB2424.namprd18.prod.outlook.com> (raw)
In-Reply-To: <MWHPR11MB1839A88FBAD5C2ECCB25CE62BFC90@MWHPR11MB1839.namprd11.prod.outlook.com>
> -----Original Message-----
> From: Hyong Youb Kim (hyonkim) <hyonkim@cisco.com>
> Sent: Wednesday, July 17, 2019 11:26 AM
> To: Nithin Kumar Dabilpuram <ndabilpuram@marvell.com>; David Marchand
> <david.marchand@redhat.com>; Thomas Monjalon
> <thomas@monjalon.net>; Ferruh Yigit <ferruh.yigit@intel.com>; Bruce
> Richardson <bruce.richardson@intel.com>
> Cc: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; John Daley (johndale)
> <johndale@cisco.com>; Shahed Shaikh <shshaikh@marvell.com>;
> dev@dpdk.org
> Subject: RE: [RFC PATCH v3 2/3] eal: add mask and unmask interrupt APIs
> > +rte_intr_mask(const struct rte_intr_handle *intr_handle) {
> > + if (intr_handle && intr_handle->type == RTE_INTR_HANDLE_VDEV)
> > + return 0;
> > +
> > + if (!intr_handle || intr_handle->fd < 0 || intr_handle->uio_cfg_fd <
> 0)
> > + return -1;
> > +
> > + switch (intr_handle->type){
> > + /* Both masking and disabling are same for UIO */
> > + case RTE_INTR_HANDLE_UIO:
> > + if (uio_intr_disable(intr_handle))
> > + return -1;
> > + break;
> > + case RTE_INTR_HANDLE_UIO_INTX:
> > + if (uio_intx_intr_disable(intr_handle))
> > + return -1;
> > + break;
> > + /* not used at this moment */
> > + case RTE_INTR_HANDLE_ALARM:
> > + return -1;
> > +#ifdef VFIO_PRESENT
> > + case RTE_INTR_HANDLE_VFIO_MSIX:
> > + case RTE_INTR_HANDLE_VFIO_MSI:
> > + return 0;
>
> Isn't this a little confusing? It returns success, but irq is not masked.
Yes. How about changing the API to rte_intr_ack()(Acknowledge the interrupt)
Or something similar? i.e replace rte_intr_unmask() with rte_intr_ack() for this use
case.
> As is, return code 0 means...
> - igb_uio: irq is masked for INTx, MSI, MSI-X
> - vfio-pci + INTx: irq is masked
> - vfio-pci + MSI/MSI-X: no changes
>
> Masking is useful only for INTx, IMO...
>
> Masking MSI/MSI-X via PCI-defined mechanisms (e.g. Mask bit in MSI-X
> Table) has no practical use for drivers. Handshaking/masking/unmasking is
> done via device/vendor specific ways, as needed. See all those
> ack/block/unblock/credit/... mechanisms used in various drivers/NICs to
> control interrupts their own way.
>
> A long time ago in early PCIe days, the linux kernel did auto-masking for
> MSI/MSI-X (i.e. mask before calling netdev irq handler). It was soon removed
> as it was unnecessary overhead (expensive PIOs to NIC for every interrupt).
> Windows and FreeBSD do not do auto-masking either.
rte_intr_ack() can abstract FreeBSD and Windows difference.
next prev parent reply other threads:[~2019-07-17 6:14 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 16:50 [dpdk-dev] [RFC PATCH] vfio: avoid re-installing irq handler Jerin Jacob Kollanukkaran
2019-07-16 5:58 ` Hyong Youb Kim (hyonkim)
2019-07-16 6:47 ` Jerin Jacob Kollanukkaran
2019-07-16 7:49 ` Hyong Youb Kim (hyonkim)
2019-07-16 9:56 ` Jerin Jacob Kollanukkaran
2019-07-16 6:46 ` [dpdk-dev] [RFC PATCH] eal: add mask and unmask interrupt apis Nithin Dabilpuram
2019-07-16 7:01 ` [dpdk-dev] [RFC PATCH v2] " Nithin Dabilpuram
2019-07-16 16:44 ` [dpdk-dev] [RFC PATCH v3 1/3] vfio: revert change that does intr eventfd setup at probe Nithin Dabilpuram
2019-07-16 16:44 ` [dpdk-dev] [RFC PATCH v3 2/3] eal: add mask and unmask interrupt APIs Nithin Dabilpuram
2019-07-17 5:55 ` Hyong Youb Kim (hyonkim)
2019-07-17 6:14 ` Jerin Jacob Kollanukkaran [this message]
2019-07-17 7:09 ` Hyong Youb Kim (hyonkim)
2019-07-17 8:03 ` Jerin Jacob Kollanukkaran
2019-07-17 8:45 ` Hyong Youb Kim (hyonkim)
2019-07-17 9:20 ` Jerin Jacob Kollanukkaran
2019-07-17 9:51 ` Hyong Youb Kim (hyonkim)
2019-07-17 10:43 ` Jerin Jacob Kollanukkaran
2019-07-17 11:06 ` Hyong Youb Kim (hyonkim)
2019-07-17 11:16 ` Jerin Jacob Kollanukkaran
2019-07-17 12:04 ` Nithin Kumar Dabilpuram
2019-07-16 16:44 ` [dpdk-dev] [RFC PATCH v3 3/3] drivers/net: use unmask API in interrupt handlers Nithin Dabilpuram
2019-07-17 6:01 ` Hyong Youb Kim (hyonkim)
2019-07-17 7:47 ` Nithin Kumar Dabilpuram
2019-07-16 20:06 ` [dpdk-dev] [RFC PATCH v3 1/3] vfio: revert change that does intr eventfd setup at probe Stephen Hemminger
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