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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/net/skfp/skfddi.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/net/skfp/skfddi.c')
-rw-r--r--drivers/net/skfp/skfddi.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/net/skfp/skfddi.c b/drivers/net/skfp/skfddi.c
index 8e4d18440a56..06ea2626c6f4 100644
--- a/drivers/net/skfp/skfddi.c
+++ b/drivers/net/skfp/skfddi.c
@@ -101,7 +101,7 @@ static const char * const boot_msg =
101static int skfp_driver_init(struct net_device *dev); 101static int skfp_driver_init(struct net_device *dev);
102static int skfp_open(struct net_device *dev); 102static int skfp_open(struct net_device *dev);
103static int skfp_close(struct net_device *dev); 103static int skfp_close(struct net_device *dev);
104static irqreturn_t skfp_interrupt(int irq, void *dev_id, struct pt_regs *regs); 104static irqreturn_t skfp_interrupt(int irq, void *dev_id);
105static struct net_device_stats *skfp_ctl_get_stats(struct net_device *dev); 105static struct net_device_stats *skfp_ctl_get_stats(struct net_device *dev);
106static void skfp_ctl_set_multicast_list(struct net_device *dev); 106static void skfp_ctl_set_multicast_list(struct net_device *dev);
107static void skfp_ctl_set_multicast_list_wo_lock(struct net_device *dev); 107static void skfp_ctl_set_multicast_list_wo_lock(struct net_device *dev);
@@ -593,7 +593,6 @@ static int skfp_close(struct net_device *dev)
593 * Arguments: 593 * Arguments:
594 * irq - interrupt vector 594 * irq - interrupt vector
595 * dev_id - pointer to device information 595 * dev_id - pointer to device information
596 * regs - pointer to registers structure
597 * 596 *
598 * Functional Description: 597 * Functional Description:
599 * This routine calls the interrupt processing routine for this adapter. It 598 * This routine calls the interrupt processing routine for this adapter. It
@@ -615,7 +614,7 @@ static int skfp_close(struct net_device *dev)
615 * Interrupts are disabled, then reenabled at the adapter. 614 * Interrupts are disabled, then reenabled at the adapter.
616 */ 615 */
617 616
618irqreturn_t skfp_interrupt(int irq, void *dev_id, struct pt_regs *regs) 617irqreturn_t skfp_interrupt(int irq, void *dev_id)
619{ 618{
620 struct net_device *dev = (struct net_device *) dev_id; 619 struct net_device *dev = (struct net_device *) dev_id;
621 struct s_smc *smc; /* private board structure pointer */ 620 struct s_smc *smc; /* private board structure pointer */