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Date:      Tue, 31 Jul 2018 19:09:43 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        bob prohaska <fbsd@www.zefox.net>
Cc:        "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>, freebsd-arm@freebsd.org
Subject:   Re: RPI3 swap experiments
Message-ID:  <2222ABBD-E689-4C3B-A7D3-50AECCC5E7B2@yahoo.com>
In-Reply-To: <20180731231912.GF94742@www.zefox.net>
References:  <20180731153531.GA94742@www.zefox.net> <201807311602.w6VG2xcN072497@pdx.rh.CN85.dnsmgr.net> <20180731191016.GD94742@www.zefox.net> <23793AAA-A339-4DEC-981F-21C7CC4FE440@yahoo.com> <20180731231912.GF94742@www.zefox.net>

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On 2018-Jul-31, at 4:19 PM, bob prohaska <fbsd AT www.zefox.net> wrote:

> On Tue, Jul 31, 2018 at 01:49:57PM -0700, Mark Millard wrote:
>> On 2018-Jul-31, at 12:10 PM, bob prohaska <fbsd at www.zefox.net> =
wrote:
>>=20
>>=20
>>> Some weeks (months?) ago there was a thread about swap being broken. =
Was
>>> that in any way related to what I'm seeing?
>>=20
>> There was some ZFS context stuff that seemed to be independent of
>> UFS stuff relative to memory use. I continue to see reports tied
>> to ZFS contexts.
>>=20
>> But I'm not sure if this is in any way related to what you are
>> calling "swap being broken". I do not remember anything about
>> swap being directly broken for swap partitions. (Swap files are
>> a different issue and are problematical.)
>>=20
>=20
> The thread I'm referring to starts with=20
> =
https://lists.freebsd.org/pipermail/freebsd-current/2018-June/069728.html =
and titled
> " swapping is completely broken in -CURRENT r334649? "
>=20
> There's no mention whether ARM is affected, just "certain hardware".=20=

> It looks like a bug was introduced in r329882 and fixed in r334752.
> Workarounds suggested  include=20
> sysctl vm.pageout_update_period=3D0
> and
> sysctl vm.pageout_update_period=3D1000.=20
>=20
> Maybe the first will turn OOMA off, and the second delay it?=20
> On  RPi the value is 600. The one correspondent who tried 1000
> said it didn't help, maybe zero is a better guess. For me it's
> a shot in total darkness either way 8-)=20

In that thread is the message:

=
https://lists.freebsd.org/pipermail/freebsd-current/2018-June/069835.html

that has a patch for dumping out more information to demsg before
it does the kill:

diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
index 264c98203c51..9c7ebcf451ec 100644
--- a/sys/vm/vm_pageout.c
+++ b/sys/vm/vm_pageout.c
@@ -1670,6 +1670,8 @@ vm_pageout_mightbe_oom(struct vm_domain *vmd, int =
page_shortage,
 	 * start OOM.  Initiate the selection and signaling of the
 	 * victim.
 	 */
+	printf("v_free_count: %u, v_inactive_count: %u\n",
+	    vmd->vmd_free_count, =
vmd->vmd_pagequeues[PQ_INACTIVE].pq_cnt);
 	vm_pageout_oom(VM_OOM_MEM);
=20
 	/*


Mark Johnston also mentions "sysctl vm" output as proving more
contextual information.



=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)




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