Re: kern/57690: XEN pvh guest GENERIC: xennet0: no rx clusters (possible mbuf/pool leak)

[Frank Kardel <kardel%netbsd.org@localhost>]

The following reply was made to PR kern/57690; it has been noted by GNATS.

From: Frank Kardel <kardel%netbsd.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/57690: XEN pvh guest GENERIC: xennet0: no rx clusters
 (possible mbuf/pool leak)
Date: Sat, 11 Nov 2023 11:35:29 +0100

 I'll close this. Seems to be a red herring. Nevertheless the VM gets 
 inoperable
 
 dropping ssh connections, barely or not responsive at the console with all
 
 VCPUs busy unable to enter kernel debugger.
 
 More in a new PR
 
 
 
 On 11/10/23 15:55, Frank Kardel wrote:
 > The following reply was made to PR kern/57690; it has been noted by GNATS.
 >
 > From: Frank Kardel <kardel%netbsd.org@localhost>
 > To: gnats-bugs%netbsd.org@localhost, kern-bug-people%netbsd.org@localhost,
 >   gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
 > Cc:
 > Subject: Re: kern/57690: XEN pvh guest GENERIC: xennet0: no rx clusters
 >   (possible mbuf/pool leak)
 > Date: Fri, 10 Nov 2023 15:50:37 +0100
 >
 >   Yes after some running time on a freshly startet VM I do
 >   
 >   see freed MBUFs and pages.
 >   
 >   Memory resource pool statistics
 >   Name        Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg
 >   Maxpg Idle
 >   xnfrx       4096   222214   17   222040 18628 18418   210 873     0
 >   inf   36
 >   
 >   There are also fails (17) here.
 >   
 >   Looking at vmstat -m it could very well be ZFS is currently eating up
 >   almost all
 >   
 >   kernel memory and I am running plain NetBSD10 without my local ZFS fixes.
 >   
 >   Frank
 >   
 >   
 >   On 11/10/23 15:00, Manuel Bouyer wrote:
 >   > The following reply was made to PR kern/57690; it has been noted by GNATS.
 >   >
 >   > From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
 >   > To: gnats-bugs%netbsd.org@localhost
 >   > Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost,
 >   >          kardel%netbsd.org@localhost
 >   > Subject: Re: kern/57690: XEN pvh guest GENERIC: xennet0: no rx clusters
 >   >   (possible mbuf/pool leak)
 >   > Date: Fri, 10 Nov 2023 14:58:22 +0100
 >   >
 >   >   On Fri, Nov 10, 2023 at 01:50:01PM +0000, Frank Kardel wrote:
 >   >   > The following reply was made to PR kern/57690; it has been noted by GNATS.
 >   >   >
 >   >   > From: Frank Kardel <kardel%netbsd.org@localhost>
 >   >   > To: gnats-bugs%netbsd.org@localhost
 >   >   > Cc:
 >   >   > Subject: Re: kern/57690: XEN pvh guest GENERIC: xennet0: no rx clusters
 >   >   >  (possible mbuf/pool leak)
 >   >   > Date: Fri, 10 Nov 2023 14:48:33 +0100
 >   >   >
 >   >   >  Well, after running a bit with a freshly started kernel I do see
 >   >   >  releases after some more traffic, so that part does
 >   >   >  seem to work.
 >   >   >
 >   >   >  Memory resource pool statistics
 >   >   >  Name        Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg
 >   >   >  Maxpg Idle
 >   >   >  xnfrx       4096   203576    6   203234  9728  9358   370   873 0   inf   28
 >   >   >
 >   >   >
 >   >   >  Why there are allocation failures and reduced performance issues still
 >   >   >  needs to be examined.
 >   >
 >   >   maybe it's a general RAM shortage ? The allocations happens from interrupt
 >   >   context, so if there is no free page it can fail.
 >   >
 >   >   Both MGETHDR and pool_cache_get_paddr() from if_xennetrxbuf_cache fails, so
 >   >   it seems just that there is no free page at some point.
 >   >
 >   >   I do see there diagnostif printfs from time to time but the system
 >   >   recovers.
 >   >
 >   >   --
 >   >   Manuel Bouyer <bouyer%antioche.eu.org@localhost>
 >   >        NetBSD: 26 ans d'experience feront toujours la difference
 >   >   --
 >   >
 >