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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/s2io.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/s2io.c')
-rw-r--r--drivers/net/s2io.c12
1 files changed, 4 insertions, 8 deletions
diff --git a/drivers/net/s2io.c b/drivers/net/s2io.c
index 1bf23e41f580..a231ab7d28dd 100644
--- a/drivers/net/s2io.c
+++ b/drivers/net/s2io.c
@@ -4029,8 +4029,7 @@ static int s2io_chk_rx_buffers(nic_t *sp, int rng_n)
4029 return 0; 4029 return 0;
4030} 4030}
4031 4031
4032static irqreturn_t 4032static irqreturn_t s2io_msi_handle(int irq, void *dev_id)
4033s2io_msi_handle(int irq, void *dev_id, struct pt_regs *regs)
4034{ 4033{
4035 struct net_device *dev = (struct net_device *) dev_id; 4034 struct net_device *dev = (struct net_device *) dev_id;
4036 nic_t *sp = dev->priv; 4035 nic_t *sp = dev->priv;
@@ -4063,8 +4062,7 @@ s2io_msi_handle(int irq, void *dev_id, struct pt_regs *regs)
4063 return IRQ_HANDLED; 4062 return IRQ_HANDLED;
4064} 4063}
4065 4064
4066static irqreturn_t 4065static irqreturn_t s2io_msix_ring_handle(int irq, void *dev_id)
4067s2io_msix_ring_handle(int irq, void *dev_id, struct pt_regs *regs)
4068{ 4066{
4069 ring_info_t *ring = (ring_info_t *)dev_id; 4067 ring_info_t *ring = (ring_info_t *)dev_id;
4070 nic_t *sp = ring->nic; 4068 nic_t *sp = ring->nic;
@@ -4078,8 +4076,7 @@ s2io_msix_ring_handle(int irq, void *dev_id, struct pt_regs *regs)
4078 return IRQ_HANDLED; 4076 return IRQ_HANDLED;
4079} 4077}
4080 4078
4081static irqreturn_t 4079static irqreturn_t s2io_msix_fifo_handle(int irq, void *dev_id)
4082s2io_msix_fifo_handle(int irq, void *dev_id, struct pt_regs *regs)
4083{ 4080{
4084 fifo_info_t *fifo = (fifo_info_t *)dev_id; 4081 fifo_info_t *fifo = (fifo_info_t *)dev_id;
4085 nic_t *sp = fifo->nic; 4082 nic_t *sp = fifo->nic;
@@ -4155,7 +4152,6 @@ static void s2io_txpic_intr_handle(nic_t *sp)
4155 * s2io_isr - ISR handler of the device . 4152 * s2io_isr - ISR handler of the device .
4156 * @irq: the irq of the device. 4153 * @irq: the irq of the device.
4157 * @dev_id: a void pointer to the dev structure of the NIC. 4154 * @dev_id: a void pointer to the dev structure of the NIC.
4158 * @pt_regs: pointer to the registers pushed on the stack.
4159 * Description: This function is the ISR handler of the device. It 4155 * Description: This function is the ISR handler of the device. It
4160 * identifies the reason for the interrupt and calls the relevant 4156 * identifies the reason for the interrupt and calls the relevant
4161 * service routines. As a contongency measure, this ISR allocates the 4157 * service routines. As a contongency measure, this ISR allocates the
@@ -4165,7 +4161,7 @@ static void s2io_txpic_intr_handle(nic_t *sp)
4165 * IRQ_HANDLED: will be returned if IRQ was handled by this routine 4161 * IRQ_HANDLED: will be returned if IRQ was handled by this routine
4166 * IRQ_NONE: will be returned if interrupt is not from our device 4162 * IRQ_NONE: will be returned if interrupt is not from our device
4167 */ 4163 */
4168static irqreturn_t s2io_isr(int irq, void *dev_id, struct pt_regs *regs) 4164static irqreturn_t s2io_isr(int irq, void *dev_id)
4169{ 4165{
4170 struct net_device *dev = (struct net_device *) dev_id; 4166 struct net_device *dev = (struct net_device *) dev_id;
4171 nic_t *sp = dev->priv; 4167 nic_t *sp = dev->priv;