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authorDavid Howells <dhowells@redhat.com>2006-10-05 09:55:46 -0400
committerDavid Howells <dhowells@warthog.cambridge.redhat.com>2006-10-05 10:10:12 -0400
commit7d12e780e003f93433d49ce78cfedf4b4c52adc5 (patch)
tree6748550400445c11a306b132009f3001e3525df8 /include/sound/sb.h
parentda482792a6d1a3fbaaa25fae867b343fb4db3246 (diff)
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
Diffstat (limited to 'include/sound/sb.h')
-rw-r--r--include/sound/sb.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/include/sound/sb.h b/include/sound/sb.h
index 431d06675e36..2dd5c8e5b4fe 100644
--- a/include/sound/sb.h
+++ b/include/sound/sb.h
@@ -100,7 +100,7 @@ struct snd_sb {
100 struct snd_rawmidi *rmidi; 100 struct snd_rawmidi *rmidi;
101 struct snd_rawmidi_substream *midi_substream_input; 101 struct snd_rawmidi_substream *midi_substream_input;
102 struct snd_rawmidi_substream *midi_substream_output; 102 struct snd_rawmidi_substream *midi_substream_output;
103 irqreturn_t (*rmidi_callback)(int irq, void *dev_id, struct pt_regs *regs); 103 irq_handler_t rmidi_callback;
104 104
105 spinlock_t reg_lock; 105 spinlock_t reg_lock;
106 spinlock_t open_lock; 106 spinlock_t open_lock;
@@ -286,7 +286,7 @@ int snd_sbdsp_reset(struct snd_sb *chip);
286int snd_sbdsp_create(struct snd_card *card, 286int snd_sbdsp_create(struct snd_card *card,
287 unsigned long port, 287 unsigned long port,
288 int irq, 288 int irq,
289 irqreturn_t (*irq_handler)(int, void *, struct pt_regs *), 289 irq_handler_t irq_handler,
290 int dma8, int dma16, 290 int dma8, int dma16,
291 unsigned short hardware, 291 unsigned short hardware,
292 struct snd_sb **r_chip); 292 struct snd_sb **r_chip);
@@ -316,7 +316,7 @@ int snd_sb16dsp_pcm(struct snd_sb *chip, int device, struct snd_pcm ** rpcm);
316const struct snd_pcm_ops *snd_sb16dsp_get_pcm_ops(int direction); 316const struct snd_pcm_ops *snd_sb16dsp_get_pcm_ops(int direction);
317int snd_sb16dsp_configure(struct snd_sb *chip); 317int snd_sb16dsp_configure(struct snd_sb *chip);
318/* sb16.c */ 318/* sb16.c */
319irqreturn_t snd_sb16dsp_interrupt(int irq, void *dev_id, struct pt_regs *regs); 319irqreturn_t snd_sb16dsp_interrupt(int irq, void *dev_id);
320 320
321/* exported mixer stuffs */ 321/* exported mixer stuffs */
322enum { 322enum {