Quick test on devices that actually exist shows that 9 devices seem to fit in
the default 8192 buffer.
So you may need many more calls, depending what size buffer you decide you can
use.
What one device looks like, FWIW (880 bytes):
D008 CUTYPE = 2107-E8, DEVTYPE = 3390-0A, VOLSER = VDL439, CYLS = 3339
CACHE DETAILS: CACHE NVS CFW DFW PINNED CONCOPY
-SUBSYSTEM Y Y N - N N
-DEVICE Y - - Y N N
DEVICE DETAILS: CCA = 08, DDC = --, DED = NO, SSD = YES, SS = 0
DUPLEX DETAILS: --
HYPERPAV DETAILS: BASE VOLUME IN POOL 8
PPRC DETAILS: PRIMARY VOLUME
CU DETAILS: SSID = D000, CUNUM = D000
FENCED STATE: NONE
HOST ACCESS: CPU PARTITION GROUPED RESERVED MPATHMODE
82C7 0E Y N Y
784A 04 Y N Y
784A 06 Y N Y
82C7 0F Y N Y
82C7 03 Y N Y
82C7 08 Y N N
Q DASD DETAILS 0000-FFFF on a test system reports that it would need over 4MB.
Since 1MB is the biggest buffer you can ask for, splitting it up is going to
have to happen anyway if you intend to run this at larger shops.
-----Original Message-----
From: Linux on 390 Port [mailto:[email protected]] On Behalf Of Marcy
Cortes
Sent: Monday, July 13, 2015 7:46 AM
To: [email protected]
Subject: Re: [LINUX-390] How to find a memory leak?
How about dividing it up in a little loop?
Issue Q D DETAILS 000-FFF, Q DA DETAILS 1000-1FFF....
-----Original Message-----
From: Linux on 390 Port [mailto:[email protected]] On Behalf Of Michael
MacIsaac
Sent: Monday, July 13, 2015 7:42 AM
To: [email protected]
Subject: Re: [LINUX-390] How to find a memory leak?
Ursula,
Any chance the requirement for contiguous memory in vmcp could be relaxed?
In my test case, 'Q DA DETAILS 0-FFFF' requires ~2.5 MB and, as I understand
it, that output can simply not be obtained through vmcp.
Thanks.
-Mike MacIsaac
On Mon, Jul 13, 2015 at 10:28 AM, Ursula Braun <[email protected]>
wrote:
> Tomas,
>
> the qeth driver has been improved in 2014 to reduce its demand for
> contiguous storage:
>
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/
> drivers/s390/net/qeth_core.h?id=d445a4e28c0ff740e946ae22860be85428814c
> 39
>
> Regards, Ursula Braun, IBM Germany, Linux on System z Dev.
>
> On Mon, 2015-07-13 at 13:39 +0000, Pavelka, Tomas wrote:
> > > I wouldn't really put that at the feet of s390 (z/Architecture).
> >
> > Bad wording on my part. When I said s390 I meant the s390 part of
> > the
> Linux kernel implementation, not the entire architecture. I meant to
> point out that the other parts of the kernel are working on getting
> out of the requirement of large contiguous buffers. AFAIK the vmcp
> driver uses the largest buffer and as you say, if the diag allowed to
> return discontiguous memory then it would solve the fragmentation
> problem. There are few other places that used larger buffers, NIC
> driver was one of them. So not sure if "all over" was the good wording
> either, maybe I should have said "multiple places" ;-)
> >
> > Tomas
> >
> > --------------------------------------------------------------------
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