From: Sagi Grimberg <sagig@dev.mellanox.co.il>
To: Steve Wise <swise@opengridcomputing.com>, fields@fieldses.org
Cc: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org
Subject: Re: [PATCH V3] svcrdma: advertise the correct max payload
Date: Wed, 24 Sep 2014 14:55:56 +0300 [thread overview]
Message-ID: <5422B14C.3040502@dev.mellanox.co.il> (raw)
In-Reply-To: <20140923221122.24227.91718.stgit@build.ogc.int>
On 9/24/2014 1:11 AM, Steve Wise wrote:
> Svcrdma currently advertises 1MB, which is too large. The correct value
> is the minimum of RPCSVC_MAXPAYLOAD and the max scatter-gather allowed
> in an NFSRDMA IO chunk * the host page size. This bug is usually benign
> because the Linux X64 NFSRDMA client correctly limits the payload size to
> the correct value (64*4096 = 256KB). But if the Linux client is PPC64
> with a 64KB page size, then the client will indeed use a payload size
> that will overflow the server.
>
Maybe I'm a bit late with this, but can you explain why SG table is
limited to 64 (fastreg MR and page_list probably bound it). Where is it
coming from? Naturally it needs to be bound by some figure, but why 64?
Sorry if I'm nit-picking on this pretty straight-forward bug fix...
Sagi.
WARNING: multiple messages have this Message-ID (diff)
From: Sagi Grimberg <sagig-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
To: Steve Wise
<swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>,
fields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH V3] svcrdma: advertise the correct max payload
Date: Wed, 24 Sep 2014 14:55:56 +0300 [thread overview]
Message-ID: <5422B14C.3040502@dev.mellanox.co.il> (raw)
In-Reply-To: <20140923221122.24227.91718.stgit-T4OLL4TyM9aNDNWfRnPdfg@public.gmane.org>
On 9/24/2014 1:11 AM, Steve Wise wrote:
> Svcrdma currently advertises 1MB, which is too large. The correct value
> is the minimum of RPCSVC_MAXPAYLOAD and the max scatter-gather allowed
> in an NFSRDMA IO chunk * the host page size. This bug is usually benign
> because the Linux X64 NFSRDMA client correctly limits the payload size to
> the correct value (64*4096 = 256KB). But if the Linux client is PPC64
> with a 64KB page size, then the client will indeed use a payload size
> that will overflow the server.
>
Maybe I'm a bit late with this, but can you explain why SG table is
limited to 64 (fastreg MR and page_list probably bound it). Where is it
coming from? Naturally it needs to be bound by some figure, but why 64?
Sorry if I'm nit-picking on this pretty straight-forward bug fix...
Sagi.
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next prev parent reply other threads:[~2014-09-24 11:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-23 22:11 [PATCH V3] svcrdma: advertise the correct max payload Steve Wise
2014-09-23 22:11 ` Steve Wise
2014-09-24 11:55 ` Sagi Grimberg [this message]
2014-09-24 11:55 ` Sagi Grimberg
2014-09-24 21:12 ` Chuck Lever
2014-09-24 21:12 ` Chuck Lever
2014-09-29 16:07 ` Steve Wise
2014-09-29 16:07 ` Steve Wise
2014-09-29 18:39 ` J. Bruce Fields
2014-09-29 18:39 ` J. Bruce Fields
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