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Date:      Sat, 16 Jun 2012 10:11:52 -0700
From:      Cy Schubert <Cy.Schubert@komquats.com>
To:        Luca Pizzamiglio <l.pizzamiglio@bally-wulff.de>
Cc:        Soeren Straarup <xride@x12.dk>, x11@freebsd.org
Subject:   Re: Intel KMS: a memory problem
Message-ID:  <201206161711.q5GHBqI6082187@slippy.cwsent.com>
In-Reply-To: Message from Luca Pizzamiglio <l.pizzamiglio@bally-wulff.de> of "Fri, 15 Jun 2012 12:41:19 %2B0200." <4FDB114F.70606@bally-wulff.de>

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It appears to have fixed my hang as well. To test I'd run find / in a 
gnome-terminal and wait for up to a minute. It used to hand hard. Playing a 
video would result in the same. All that's working now.


-- 
Cheers,
Cy Schubert <Cy.Schubert@komquats.com>
FreeBSD UNIX:  <cy@FreeBSD.org>   Web:  http://www.FreeBSD.org



In message <4FDB114F.70606@bally-wulff.de>, Luca Pizzamiglio writes:
> Hi Konstantin,
> 
> I'm not able to repeat the panic. It seems that you've found the issue!
> Thanks a lot, it works great!
> 
> Best regards,
> Luca
> 
> 
> On 06/14/12 19:34, Konstantin Belousov wrote:
> > On Thu, Jun 14, 2012 at 08:06:23PM +0300, Konstantin Belousov wrote:
> >> On Thu, Jun 14, 2012 at 09:29:40AM +0200, Luca Pizzamiglio wrote:
> >>> On 06/13/12 13:26, Konstantin Belousov wrote:
> >>>> On Wed, Jun 13, 2012 at 12:40:19PM +0200, Luca Pizzamiglio wrote:
> >>>>> Hi people,
> >>>>>
> >>>>> I'm using 9-RELENG with KMS and the last port updated on a SandyBridge
> >>>>> platform (Intel Graphics)
> >>>>> With a quite simple openGL application, a panic occurred:
> >>>>>
> >>>>> panic: pmap_mapdev: Couldn't alloc kernel virtual memory
> >>>>> Tracing pid 944 tid 100105 td 0xca85c8a0
> >>>>> kdb_enter(c0ffe535,c0ffe535,c103dcff,efa62ac0,1,...) at kdb_enter+0x3a
> >>>>> panic(c103dcff,5000,c9879151,0,c1a02000,...) at panic+0x18c
> >>>>> pmap_mapdev_attr(c1a02000,4800,1,1,c911d980,...) at pmap_mapdev_attr+0x
> 7e
> >>>>> i915_gem_obj_io(2d014008,0,4800,0,0,...) at i915_gem_obj_io+0x513
> >>>>> i915_gem_pwrite_ioctl(c9925800,ca827120,ca871300,c0a78b5b,efa62bd4,...)
> >>>>> at i915_gem_pwrite_ioctl+0x4b
> >>>>> drm_ioctl(c97e0400,8020645d,ca827120,3,ca85c8a0,...) at drm_ioctl+0x2d8
> >>>>> devfs_ioctl_f(c91cb850,8020645d,ca827120,c91b5e80,ca85c8a0,...) at
> >>>>> devfs_ioctl_f+0x10a
> >>>>> kern_ioctl(ca85c8a0,4,8020645d,ca827120,a62ccc,...) at kern_ioctl+0x2a0
> >>>>> sys_ioctl(ca85c8a0,efa62ccc,c67c4c80,293d3b4e,1,...) at sys_ioctl+0x134
> >>>>> syscall(efa62d08) at syscall+0x34a
> >>>>> Xint0x80_syscall() at Xint0x80_syscall+0x21
> >>>>> --- syscall (54, FreeBSD ELF32, sys_ioctl), eip = 0x293d5b93, esp =
> >>>>> 0xbfbf7f4c, ebp = 0xbfbf7f68 ---
> >>>>>
> >>>>> I tried to increase vm.kmem_size and vm.kmem_size_max to 512M, but the
> >>>>> problem persists.
> >>>>>
> >>>>> Any easy idea or workaround?
> >>>>> In the meanwhile, I'll try to investigate this problem deeper.
> >>>>
> >>>> You are probably first who run 32bit kernel on SandyBridge + GEMified
> >>>> i915 driver.
> >>>>
> >>>>  From the trace you provided it seems that kernel was unable to find
> >>>> a free area in KVA for 5 consequtive pages. I would think that you have
> >>>> relatively high fragmentation of KVA. What load on machine is ?
> >>>>
> >>>> Actually, quite some time ago, i915_gem_gtt_write() did mapped gtt
> >>>> page by page, instead of mapping the whole range of pages undergoing i/o
> .
> >>>> I was pointed out that this was major performance bootleneck for GTT
> >>>> mapped objects. It might be reasonable to restore the slow mode for
> >>>> 32bit kernels, since people running such kernels on SandyBridge definite
> ly
> >>>> do not care about performance.
> >>>>
> >>>
> >>> Hi Konstantin,
> >>> Thanks for the quick reply!
> >>> yes, maybe I'm the first using 32bit architecture on SandyBridge, but
> >>> for some internal conflicts (human ones) I should use 32 bit version and
> >>> performance is an important topic.
> >>> It's quite strange what are you saying about KVA fragmentation, the load
> >>> of the machine is really low < 0.3; test scenario is: boot, starting X
> >>> with twm and launching our openGL application.. after a couple of
> >>> minutes, it panics. The openGL application draw a black screen and some
> >>> lines to show performance indexes, like CPU percentage usage, time per
> >>> frame, and so on. CPU percentage is about 7-9%.
> >>> The system has 4 GB of memory, but only 3GB are addressable.
> >>> Any idea how could I monitor memory fragmentation?
> >> Ok, there was second report of the same panic.
> >>
> >> Please apply the debugging patch from the end of message, and show
> >> me the panic message after.
> >>
> >>>
> >>> I would like to try PAE extension to address more memory or use 64 bit
> >>> world with the 32 bit compatibility layer. PAE extension is easy to
> >>> test, but for 64bit I need to delete&reinstall&recompile everything...
> >>
> >> I am sure that i915 does not work with PAE, probably not even compiles.
> >>
> >> diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
> >> index d02f00e..e15d24f 100644
> >> --- a/sys/i386/i386/pmap.c
> >> +++ b/sys/i386/i386/pmap.c
> >> @@ -4983,8 +4983,10 @@ pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int
>  mode)
> >>   		va = KERNBASE + pa;
> >>   	else
> >>   		va = kmem_alloc_nofault(kernel_map, size);
> >> -	if (!va)
> >> -		panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
> >> +	if (va == 0) {
> >> +		panic("pmap_mapdev: Couldn't alloc kernel virtual memory, "
> >> +		    "size %d", size);
> >> +	}
> >>
> >>   	for (tmpsize = 0; tmpsize < size; tmpsize += PAGE_SIZE)
> >>   		pmap_kenter_attr(va + tmpsize, pa + tmpsize, mode);
> >
> > Hm, I think I see an issue that could be very well the cause of the
> > trouble. Please also apply the patch below.
> >
> > diff --git a/sys/dev/drm2/i915/i915_gem.c b/sys/dev/drm2/i915/i915_gem.c
> > index ca531fb..73c0b53 100644
> > --- a/sys/dev/drm2/i915/i915_gem.c
> > +++ b/sys/dev/drm2/i915/i915_gem.c
> > @@ -1064,7 +1064,7 @@ i915_gem_gtt_write(struct drm_device *dev, struct drm
> _i915_gem_object *obj,
> >   	    IDX_TO_OFF(obj_pi), size, PAT_WRITE_COMBINING);
> >   	ret = -copyin_nofault((void *)(uintptr_t)data_ptr, (char *)mkva +
> >   	    obj_po, size);
> > -	pmap_unmapdev(mkva, PAGE_SIZE);
> > +	pmap_unmapdev(mkva, size);
> >   	return (ret);
> >   }
> >
> >
> 
> 
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