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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/chelsio
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/chelsio')
-rw-r--r--drivers/net/chelsio/cxgb2.c2
-rw-r--r--drivers/net/chelsio/sge.c6
-rw-r--r--drivers/net/chelsio/sge.h9
3 files changed, 5 insertions, 12 deletions
diff --git a/drivers/net/chelsio/cxgb2.c b/drivers/net/chelsio/cxgb2.c
index 5f1b06753462..ad7ff9641a7e 100644
--- a/drivers/net/chelsio/cxgb2.c
+++ b/drivers/net/chelsio/cxgb2.c
@@ -918,7 +918,7 @@ static void t1_netpoll(struct net_device *dev)
918 struct adapter *adapter = dev->priv; 918 struct adapter *adapter = dev->priv;
919 919
920 local_irq_save(flags); 920 local_irq_save(flags);
921 t1_select_intr_handler(adapter)(adapter->pdev->irq, adapter, NULL); 921 t1_select_intr_handler(adapter)(adapter->pdev->irq, adapter);
922 local_irq_restore(flags); 922 local_irq_restore(flags);
923} 923}
924#endif 924#endif
diff --git a/drivers/net/chelsio/sge.c b/drivers/net/chelsio/sge.c
index ddd0bdb498f4..9799c12380fc 100644
--- a/drivers/net/chelsio/sge.c
+++ b/drivers/net/chelsio/sge.c
@@ -1217,7 +1217,7 @@ static inline int napi_is_scheduled(struct net_device *dev)
1217/* 1217/*
1218 * NAPI version of the main interrupt handler. 1218 * NAPI version of the main interrupt handler.
1219 */ 1219 */
1220static irqreturn_t t1_interrupt_napi(int irq, void *data, struct pt_regs *regs) 1220static irqreturn_t t1_interrupt_napi(int irq, void *data)
1221{ 1221{
1222 int handled; 1222 int handled;
1223 struct adapter *adapter = data; 1223 struct adapter *adapter = data;
@@ -1279,7 +1279,7 @@ static irqreturn_t t1_interrupt_napi(int irq, void *data, struct pt_regs *regs)
1279 * 5. If we took an interrupt, but no valid respQ descriptors was found we 1279 * 5. If we took an interrupt, but no valid respQ descriptors was found we
1280 * let the slow_intr_handler run and do error handling. 1280 * let the slow_intr_handler run and do error handling.
1281 */ 1281 */
1282static irqreturn_t t1_interrupt(int irq, void *cookie, struct pt_regs *regs) 1282static irqreturn_t t1_interrupt(int irq, void *cookie)
1283{ 1283{
1284 int work_done; 1284 int work_done;
1285 struct respQ_e *e; 1285 struct respQ_e *e;
@@ -1312,7 +1312,7 @@ static irqreturn_t t1_interrupt(int irq, void *cookie, struct pt_regs *regs)
1312 return IRQ_RETVAL(work_done != 0); 1312 return IRQ_RETVAL(work_done != 0);
1313} 1313}
1314 1314
1315intr_handler_t t1_select_intr_handler(adapter_t *adapter) 1315irq_handler_t t1_select_intr_handler(adapter_t *adapter)
1316{ 1316{
1317 return adapter->params.sge.polling ? t1_interrupt_napi : t1_interrupt; 1317 return adapter->params.sge.polling ? t1_interrupt_napi : t1_interrupt;
1318} 1318}
diff --git a/drivers/net/chelsio/sge.h b/drivers/net/chelsio/sge.h
index 6d0d24a6364f..91af47bab7be 100644
--- a/drivers/net/chelsio/sge.h
+++ b/drivers/net/chelsio/sge.h
@@ -43,13 +43,6 @@
43#include <linux/interrupt.h> 43#include <linux/interrupt.h>
44#include <asm/byteorder.h> 44#include <asm/byteorder.h>
45 45
46#ifndef IRQ_RETVAL
47#define IRQ_RETVAL(x)
48typedef void irqreturn_t;
49#endif
50
51typedef irqreturn_t (*intr_handler_t)(int, void *, struct pt_regs *);
52
53struct sge_intr_counts { 46struct sge_intr_counts {
54 unsigned int respQ_empty; /* # times respQ empty */ 47 unsigned int respQ_empty; /* # times respQ empty */
55 unsigned int respQ_overflow; /* # respQ overflow (fatal) */ 48 unsigned int respQ_overflow; /* # respQ overflow (fatal) */
@@ -88,7 +81,7 @@ struct sge *t1_sge_create(struct adapter *, struct sge_params *);
88int t1_sge_configure(struct sge *, struct sge_params *); 81int t1_sge_configure(struct sge *, struct sge_params *);
89int t1_sge_set_coalesce_params(struct sge *, struct sge_params *); 82int t1_sge_set_coalesce_params(struct sge *, struct sge_params *);
90void t1_sge_destroy(struct sge *); 83void t1_sge_destroy(struct sge *);
91intr_handler_t t1_select_intr_handler(adapter_t *adapter); 84irq_handler_t t1_select_intr_handler(adapter_t *adapter);
92int t1_start_xmit(struct sk_buff *skb, struct net_device *dev); 85int t1_start_xmit(struct sk_buff *skb, struct net_device *dev);
93void t1_set_vlan_accel(struct adapter *adapter, int on_off); 86void t1_set_vlan_accel(struct adapter *adapter, int on_off);
94void t1_sge_start(struct sge *); 87void t1_sge_start(struct sge *);