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<p class="MsoNormal">No, it is not necessary to tune map_on_demand with modern NICs/MOFED drivers. Latest Lustre can only accept values of 0 or 1. This forces (0) the use of global memory regions (when available), but global MR API was removed (or deprecated?)
by Mellanox. A recent change was made to default map_on_demand to 1 (LU-15186) so FMR/FastReg is used by default even if global MR is available. We expect global MR to be removed completely at some point.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Chris Horn<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Thomas Roth <t.roth@gsi.de><br>
<b>Date: </b>Monday, January 31, 2022 at 5:31 AM<br>
<b>To: </b>Horn, Chris <chris.horn@hpe.com>, lustre-discuss@lists.lustre.org <lustre-discuss@lists.lustre.org><br>
<b>Subject: </b>Re: [lustre-discuss] 'queue depth too large', but connection works<o:p></o:p></span></p>
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<p class="MsoNormal">Very good!<br>
<br>
Digging a bit more into the ko2iblnd parameters, it seems the default for 'map_on_demand' comes out as '1' - both on mlx4 and mlx5 boxes.<br>
I was reading about earlier issues with in rdma, which supposedly pushed the default to 256 - but that was perhaps to long ago.<br>
Is it necessary to tune this parameter nowadays?<br>
<br>
Regards<br>
Thomas<br>
<br>
<br>
On 1/30/22 20:41, Horn, Chris wrote:<br>
> Yes, this means the server has peer_credits=8, so can only accept that value. It informs the client of this so subsequent client connection attempt uses the lower value.<br>
> ________________________________<br>
> From: lustre-discuss <lustre-discuss-bounces@lists.lustre.org> on behalf of Thomas Roth <t.roth@gsi.de><br>
> Sent: Saturday, January 29, 2022 11:46 AM<br>
> To: lustre-discuss@lists.lustre.org <lustre-discuss@lists.lustre.org><br>
> Subject: [lustre-discuss] 'queue depth too large', but connection works<br>
> <br>
> Dear all,<br>
> <br>
> test system: servers 2.12.7, and a client 2.12.6., all mlx4.<br>
> <br>
> The client has some non-default ko2iblnd parameters, including "peer_credits=16".<br>
> <br>
> I mounted my test system there and happily copied around some directories. Only afterwards I found<br>
> > LNetError: 5278:0:(o2iblnd_cb.c:2551:kiblnd_passive_connect()) Can't accept conn from 10.20.3.64@o2ib6, queue depth too large: 16 (<=8 wanted)<br>
> in the MDS log.<br>
> <br>
> I did read LU-3322, but obviously did not the point. "Can't accept conn" used to deny client access, but the MDS that didn't like my client just<br>
> created some ~25k new objects on behalf of that client.<br>
> <br>
> Does this mean client and server negotiate a suitable value, but behind the scenes?<br>
> <br>
> Regards,<br>
> Thomas<br>
> _______________________________________________<br>
> lustre-discuss mailing list<br>
> lustre-discuss@lists.lustre.org<br>
> <a href="http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org">http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org</a>
<br>
> <o:p></o:p></p>
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