From: Jason Gunthorpe <jgg@ziepe.ca>
To: Long Li <longli@microsoft.com>
Cc: Wei Hu <weh@microsoft.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
Ajay Sharma <sharmaajay@microsoft.com>,
"leon@kernel.org" <leon@kernel.org>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
Dexuan Cui <decui@microsoft.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"edumazet@google.com" <edumazet@google.com>,
"kuba@kernel.org" <kuba@kernel.org>,
"pabeni@redhat.com" <pabeni@redhat.com>,
vkuznets <vkuznets@redhat.com>,
"ssengar@linux.microsoft.com" <ssengar@linux.microsoft.com>,
"shradhagupta@linux.microsoft.com"
<shradhagupta@linux.microsoft.com>
Subject: Re: [PATCH v4 1/1] RDMA/mana_ib: Add EQ interrupt support to mana ib driver.
Date: Tue, 1 Aug 2023 20:46:03 -0300 [thread overview]
Message-ID: <ZMmZO9IPmXNEB49t@ziepe.ca> (raw)
In-Reply-To: <PH7PR21MB326367A455B78A1F230C5C34CE0AA@PH7PR21MB3263.namprd21.prod.outlook.com>
On Tue, Aug 01, 2023 at 07:06:57PM +0000, Long Li wrote:
> The driver interrupt code limits the CPU processing time of each EQ
> by reading a small batch of EQEs in this interrupt. It guarantees
> all the EQs are checked on this CPU, and limits the interrupt
> processing time for any given EQ. In this way, a bad EQ (which is
> stormed by a bad user doing unreasonable re-arming on the CQ) can't
> storm other EQs on this CPU.
Of course it can, the bad use just creates a million EQs and pushes a
bit of work through them constantly. How is that really any different
from pushing more EQEs into a single EQ?
And how does your EQ multiplexing work anyhow? Do you poll every EQ on
every interrupt? That itself is a DOS vector.
Jason
next prev parent reply other threads:[~2023-08-01 23:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-28 17:07 [PATCH v4 1/1] RDMA/mana_ib: Add EQ interrupt support to mana ib driver Wei Hu
2023-07-28 17:43 ` Jason Gunthorpe
2023-07-28 17:51 ` Long Li
2023-07-28 18:02 ` Jason Gunthorpe
2023-07-28 18:22 ` Long Li
2023-07-28 18:39 ` Jason Gunthorpe
2023-08-01 19:06 ` Long Li
2023-08-01 23:46 ` Jason Gunthorpe [this message]
2023-08-02 4:11 ` [EXTERNAL] " Ajay Sharma
2023-08-02 13:08 ` Jason Gunthorpe
2023-08-15 22:51 ` Long Li
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