7d12e780e0
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) |
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.. | ||
Kconfig | ||
Makefile | ||
README | ||
README.ioctl | ||
bus-osm.c | ||
config-osm.c | ||
core.h | ||
debug.c | ||
device.c | ||
driver.c | ||
exec-osm.c | ||
i2o_block.c | ||
i2o_block.h | ||
i2o_config.c | ||
i2o_lan.h | ||
i2o_proc.c | ||
i2o_scsi.c | ||
iop.c | ||
pci.c |
README
Linux I2O Support (c) Copyright 1999 Red Hat Software and others. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. AUTHORS (so far) Alan Cox, Building Number Three Ltd. Core code, SCSI and Block OSMs Steve Ralston, LSI Logic Corp. Debugging SCSI and Block OSM Deepak Saxena, Intel Corp. Various core/block extensions /proc interface, bug fixes Ioctl interfaces for control Debugging LAN OSM Philip Rumpf Fixed assorted dumb SMP locking bugs Juha Sievanen, University of Helsinki Finland LAN OSM code /proc interface to LAN class Bug fixes Core code extensions Auvo Häkkinen, University of Helsinki Finland LAN OSM code /Proc interface to LAN class Bug fixes Core code extensions Taneli Vähäkangas, University of Helsinki Finland Fixes to i2o_config CREDITS This work was made possible by Red Hat Software Funding for the Building #3 part of the project Symbios Logic (Now LSI) Host adapters, hints, known to work platforms when I hit compatibility problems BoxHill Corporation Loan of initial FibreChannel disk array used for development work. European Comission Funding the work done by the University of Helsinki SysKonnect Loan of FDDI and Gigabit Ethernet cards ASUSTeK Loan of I2O motherboard STATUS: o The core setup works within limits. o The scsi layer seems to almost work. I'm still chasing down the hang bug. o The block OSM is mostly functional o LAN OSM works with FDDI and Ethernet cards. TO DO: General: o Provide hidden address space if asked o Long term message flow control o PCI IOP's without interrupts are not supported yet o Push FAIL handling into the core o DDM control interfaces for module load etc o Add I2O 2.0 support (Deffered to 2.5 kernel) Block: o Multiple major numbers o Read ahead and cache handling stuff. Talk to Ingo and people o Power management o Finish Media changers SCSI: o Find the right way to associate drives/luns/busses Lan: o Performance tuning o Test Fibre Channel code Tape: o Anyone seen anything implementing this ? (D.S: Will attempt to do so if spare cycles permit)