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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 /drivers/input/mouse/sermouse.c
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 'drivers/input/mouse/sermouse.c')
-rw-r--r--drivers/input/mouse/sermouse.c14
1 files changed, 5 insertions, 9 deletions
diff --git a/drivers/input/mouse/sermouse.c b/drivers/input/mouse/sermouse.c
index 680b32353884..2a272c5daf08 100644
--- a/drivers/input/mouse/sermouse.c
+++ b/drivers/input/mouse/sermouse.c
@@ -61,13 +61,11 @@ struct sermouse {
61 * second, which is as good as a PS/2 or USB mouse. 61 * second, which is as good as a PS/2 or USB mouse.
62 */ 62 */
63 63
64static void sermouse_process_msc(struct sermouse *sermouse, signed char data, struct pt_regs *regs) 64static void sermouse_process_msc(struct sermouse *sermouse, signed char data)
65{ 65{
66 struct input_dev *dev = sermouse->dev; 66 struct input_dev *dev = sermouse->dev;
67 signed char *buf = sermouse->buf; 67 signed char *buf = sermouse->buf;
68 68
69 input_regs(dev, regs);
70
71 switch (sermouse->count) { 69 switch (sermouse->count) {
72 70
73 case 0: 71 case 0:
@@ -104,15 +102,13 @@ static void sermouse_process_msc(struct sermouse *sermouse, signed char data, st
104 * standard 3-byte packets and 1200 bps. 102 * standard 3-byte packets and 1200 bps.
105 */ 103 */
106 104
107static void sermouse_process_ms(struct sermouse *sermouse, signed char data, struct pt_regs *regs) 105static void sermouse_process_ms(struct sermouse *sermouse, signed char data)
108{ 106{
109 struct input_dev *dev = sermouse->dev; 107 struct input_dev *dev = sermouse->dev;
110 signed char *buf = sermouse->buf; 108 signed char *buf = sermouse->buf;
111 109
112 if (data & 0x40) sermouse->count = 0; 110 if (data & 0x40) sermouse->count = 0;
113 111
114 input_regs(dev, regs);
115
116 switch (sermouse->count) { 112 switch (sermouse->count) {
117 113
118 case 0: 114 case 0:
@@ -206,7 +202,7 @@ static void sermouse_process_ms(struct sermouse *sermouse, signed char data, str
206 */ 202 */
207 203
208static irqreturn_t sermouse_interrupt(struct serio *serio, 204static irqreturn_t sermouse_interrupt(struct serio *serio,
209 unsigned char data, unsigned int flags, struct pt_regs *regs) 205 unsigned char data, unsigned int flags)
210{ 206{
211 struct sermouse *sermouse = serio_get_drvdata(serio); 207 struct sermouse *sermouse = serio_get_drvdata(serio);
212 208
@@ -214,9 +210,9 @@ static irqreturn_t sermouse_interrupt(struct serio *serio,
214 sermouse->last = jiffies; 210 sermouse->last = jiffies;
215 211
216 if (sermouse->type > SERIO_SUN) 212 if (sermouse->type > SERIO_SUN)
217 sermouse_process_ms(sermouse, data, regs); 213 sermouse_process_ms(sermouse, data);
218 else 214 else
219 sermouse_process_msc(sermouse, data, regs); 215 sermouse_process_msc(sermouse, data);
220 return IRQ_HANDLED; 216 return IRQ_HANDLED;
221} 217}
222 218