Re: [Intel-gfx] [PATCH 04/10] drm/i915: move intel_context slab to direct module init/exit

[Jason Ekstrand <jason@jlekstrand.net>]

On Mon, Jul 26, 2021 at 3:35 AM Tvrtko Ursulin
<tvrtko.ursulin@linux.intel.com> wrote:
>
>
> On 23/07/2021 20:29, Daniel Vetter wrote:
> > With the global kmem_cache shrink infrastructure gone there's nothing
> > special and we can convert them over.
> >
> > I'm doing this split up into each patch because there's quite a bit of
> > noise with removing the static global.slab_ce to just a
> > slab_ce.
> >
> > Cc: Jason Ekstrand <jason@jlekstrand.net>
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > ---
> >   drivers/gpu/drm/i915/gt/intel_context.c | 25 ++++++++-----------------
> >   drivers/gpu/drm/i915/gt/intel_context.h |  3 +++
> >   drivers/gpu/drm/i915/i915_globals.c     |  2 --
> >   drivers/gpu/drm/i915/i915_globals.h     |  1 -
> >   drivers/gpu/drm/i915/i915_pci.c         |  2 ++
> >   5 files changed, 13 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> > index baa05fddd690..283382549a6f 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_context.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_context.c
> > @@ -7,7 +7,6 @@
> >   #include "gem/i915_gem_pm.h"
> >
> >   #include "i915_drv.h"
> > -#include "i915_globals.h"
> >   #include "i915_trace.h"
> >
> >   #include "intel_context.h"
> > @@ -15,14 +14,11 @@
> >   #include "intel_engine_pm.h"
> >   #include "intel_ring.h"
> >
> > -static struct i915_global_context {
> > -     struct i915_global base;
> > -     struct kmem_cache *slab_ce;
> > -} global;
> > +struct kmem_cache *slab_ce;

Static?  With that,

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

> >
> >   static struct intel_context *intel_context_alloc(void)
> >   {
> > -     return kmem_cache_zalloc(global.slab_ce, GFP_KERNEL);
> > +     return kmem_cache_zalloc(slab_ce, GFP_KERNEL);
> >   }
> >
> >   static void rcu_context_free(struct rcu_head *rcu)
> > @@ -30,7 +26,7 @@ static void rcu_context_free(struct rcu_head *rcu)
> >       struct intel_context *ce = container_of(rcu, typeof(*ce), rcu);
> >
> >       trace_intel_context_free(ce);
> > -     kmem_cache_free(global.slab_ce, ce);
> > +     kmem_cache_free(slab_ce, ce);
> >   }
> >
> >   void intel_context_free(struct intel_context *ce)
> > @@ -410,22 +406,17 @@ void intel_context_fini(struct intel_context *ce)
> >       i915_active_fini(&ce->active);
> >   }
> >
> > -static void i915_global_context_exit(void)
> > +void i915_context_module_exit(void)
> >   {
> > -     kmem_cache_destroy(global.slab_ce);
> > +     kmem_cache_destroy(slab_ce);
> >   }
> >
> > -static struct i915_global_context global = { {
> > -     .exit = i915_global_context_exit,
> > -} };
> > -
> > -int __init i915_global_context_init(void)
> > +int __init i915_context_module_init(void)
> >   {
> > -     global.slab_ce = KMEM_CACHE(intel_context, SLAB_HWCACHE_ALIGN);
> > -     if (!global.slab_ce)
> > +     slab_ce = KMEM_CACHE(intel_context, SLAB_HWCACHE_ALIGN);
> > +     if (!slab_ce)
> >               return -ENOMEM;
> >
> > -     i915_global_register(&global.base);
> >       return 0;
> >   }
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
> > index 974ef85320c2..a0ca82e3c40d 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_context.h
> > +++ b/drivers/gpu/drm/i915/gt/intel_context.h
> > @@ -30,6 +30,9 @@ void intel_context_init(struct intel_context *ce,
> >                       struct intel_engine_cs *engine);
> >   void intel_context_fini(struct intel_context *ce);
> >
> > +void i915_context_module_exit(void);
> > +int i915_context_module_init(void);
> > +
> >   struct intel_context *
> >   intel_context_create(struct intel_engine_cs *engine);
> >
> > diff --git a/drivers/gpu/drm/i915/i915_globals.c b/drivers/gpu/drm/i915/i915_globals.c
> > index 3de7cf22ec76..d36eb7dc40aa 100644
> > --- a/drivers/gpu/drm/i915/i915_globals.c
> > +++ b/drivers/gpu/drm/i915/i915_globals.c
> > @@ -7,7 +7,6 @@
> >   #include <linux/slab.h>
> >   #include <linux/workqueue.h>
> >
> > -#include "gem/i915_gem_context.h"
> >   #include "gem/i915_gem_object.h"
> >   #include "i915_globals.h"
> >   #include "i915_request.h"
> > @@ -32,7 +31,6 @@ static void __i915_globals_cleanup(void)
> >   }
> >
> >   static __initconst int (* const initfn[])(void) = {
> > -     i915_global_context_init,
> >       i915_global_gem_context_init,
> >       i915_global_objects_init,
> >       i915_global_request_init,
> > diff --git a/drivers/gpu/drm/i915/i915_globals.h b/drivers/gpu/drm/i915/i915_globals.h
> > index d80901ba75e3..60daa738a188 100644
> > --- a/drivers/gpu/drm/i915/i915_globals.h
> > +++ b/drivers/gpu/drm/i915/i915_globals.h
> > @@ -23,7 +23,6 @@ int i915_globals_init(void);
> >   void i915_globals_exit(void);
> >
> >   /* constructors */
> > -int i915_global_context_init(void);
> >   int i915_global_gem_context_init(void);
> >   int i915_global_objects_init(void);
> >   int i915_global_request_init(void);
> > diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
> > index f9527269e30a..266618157775 100644
> > --- a/drivers/gpu/drm/i915/i915_pci.c
> > +++ b/drivers/gpu/drm/i915/i915_pci.c
> > @@ -33,6 +33,7 @@
> >   #include "i915_active.h"
> >   #include "i915_buddy.h"
> >   #include "i915_drv.h"
> > +#include "gem/i915_gem_context.h"
>
> It's a bit ugly to go to a design where i915_pci.c has to include so
> many random parts of i915. IMO for a complex driver like i915,
> compartmentalizing so much knowledge about the internals was better
> inside the globals layer.

I agree that i915_pci feels like the wrong place to put this but I
don't think that's so much because globals don't belong in i915_pci
but because i915_init/exit don't belong there.  Maybe, once this is
all said and done (or at the start of the series), we should move
i915_init/exit to i915_drv.c?  Of course, there's a bunch of PCI
probing stuff in i915_drv.c so..... yeah.... our organization is
pretty busted.

--Jason

> Maybe add a cover letter to explain the perceived pros and cons and
> thinking in general?
>
> Regards,
>
> Tvrtko
>
> >   #include "i915_perf.h"
> >   #include "i915_globals.h"
> >   #include "i915_selftest.h"
> > @@ -1297,6 +1298,7 @@ static const struct {
> >       { i915_check_nomodeset, NULL },
> >       { i915_active_module_init, i915_active_module_exit },
> >       { i915_buddy_module_init, i915_buddy_module_exit },
> > +     { i915_context_module_init, i915_context_module_exit },
> >       { i915_globals_init, i915_globals_exit },
> >       { i915_mock_selftests, NULL },
> >       { i915_pmu_init, i915_pmu_exit },
> >
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