linux/lib/Makefile, branch v2.6.20

[PATCH] uml problems with linux/io.h

2006-12-13T17:05:52Z

Remove useless includes of linux/io.h, don't even try to build iomap_copy on uml (it doesn't have readb() et.al., so...) Signed-off-by: Al Viro Acked-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] SLAB: use a multiply instead of a divide in obj_to_index()

2006-12-13T17:05:49Z

When some objects are allocated by one CPU but freed by another CPU we can consume lot of cycles doing divides in obj_to_index(). (Typical load on a dual processor machine where network interrupts are handled by one particular CPU (allocating skbufs), and the other CPU is running the application (consuming and freeing skbufs)) Here on one production server (dual-core AMD Opteron 285), I noticed this divide took 1.20 % of CPU_CLK_UNHALTED events in kernel. But Opteron are quite modern cpus and the divide is much more expensive on oldest architectures : On a 200 MHz sparcv9 machine, the division takes 64 cycles instead of 1 cycle for a multiply. Doing some math, we can use a reciprocal multiplication instead of a divide. If we want to compute V = (A / B) (A and B being u32 quantities) we can instead use : V = ((u64)A * RECIPROCAL(B)) >> 32 ; where RECIPROCAL(B) is precalculated to ((1LL << 32) + (B - 1)) / B Note : I wrote pure C code for clarity. gcc output for i386 is not optimal but acceptable : mull 0x14(%ebx) mov %edx,%eax // part of the >> 32 xor %edx,%edx // useless mov %eax,(%esp) // could be avoided mov %edx,0x4(%esp) // useless mov (%esp),%ebx [akpm@osdl.org: small cleanups] Signed-off-by: Eric Dumazet Cc: Christoph Lameter Cc: David Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] fault-injection capabilities infrastructure

2006-12-08T16:29:02Z

This patch provides base functions implement to fault-injection capabilities. - The function should_fail() is taken from failmalloc-1.0 (http://www.nongnu.org/failmalloc/) [akpm@osdl.org: cleanups, comments, add __init] Cc: Signed-off-by: Akinobu Mita Signed-off-by: Don Mullis Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] bit reverse library

2006-12-08T16:28:39Z

This patch provides two bit reverse functions and bit reverse table. - reverse the order of bits in a u32 value u8 bitrev8(u8 x); - reverse the order of bits in a u32 value u32 bitrev32(u32 x); - byte reverse table const u8 byte_rev_table[256]; Signed-off-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] Generic BUG implementation

2006-12-08T16:28:39Z

This patch adds common handling for kernel BUGs, for use by architectures as they wish. The code is derived from arch/powerpc. The advantages of having common BUG handling are: - consistent BUG reporting across architectures - shared implementation of out-of-line file/line data - implement CONFIG_DEBUG_BUGVERBOSE consistently This means that in inline impact of BUG is just the illegal instruction itself, which is an improvement for i386 and x86-64. A BUG is represented in the instruction stream as an illegal instruction, which has file/line information associated with it. This extra information is stored in the __bug_table section in the ELF file. When the kernel gets an illegal instruction, it first confirms it might possibly be from a BUG (ie, in kernel mode, the right illegal instruction). It then calls report_bug(). This searches __bug_table for a matching instruction pointer, and if found, prints the corresponding file/line information. If report_bug() determines that it wasn't a BUG which caused the trap, it returns BUG_TRAP_TYPE_NONE. Some architectures (powerpc) implement WARN using the same mechanism; if the illegal instruction was the result of a WARN, then report_bug(Q) returns CONFIG_DEBUG_BUGVERBOSE; otherwise it returns BUG_TRAP_TYPE_BUG. lib/bug.c keeps a list of loaded modules which can be searched for __bug_table entries. The architecture must call module_bug_finalize()/module_bug_cleanup() from its corresponding module_finalize/cleanup functions. Unsetting CONFIG_DEBUG_BUGVERBOSE will reduce the kernel size by some amount. At the very least, filename and line information will not be recorded for each but, but architectures may decide to store no extra information per BUG at all. Unfortunately, gcc doesn't have a general way to mark an asm() as noreturn, so architectures will generally have to include an infinite loop (or similar) in the BUG code, so that gcc knows execution won't continue beyond that point. gcc does have a __builtin_trap() operator which may be useful to achieve the same effect, unfortunately it cannot be used to actually implement the BUG itself, because there's no way to get the instruction's address for use in generating the __bug_table entry. [randy.dunlap@oracle.com: Handle BUG=n, GENERIC_BUG=n to prevent build errors] [bunk@stusta.de: include/linux/bug.h must always #include Cc: Andi Kleen Cc: Hugh Dickens Cc: Michael Ellerman Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Rusty Russell Signed-off-by: Adrian Bunk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] lib functions: always build hweight for loadable modules

2006-12-07T16:39:42Z

Always build hweight8/16/32/64() functions into the kernel so that loadable modules may use them. I didn't remove GENERIC_HWEIGHT since ALPHA_EV67, ia64, and some variants of UltraSparc(64) provide their own hweight functions. Fixes config/build problems with NTFS=m and JOYSTICK_ANALOG=m. Kernel: arch/x86_64/boot/bzImage is ready (#19) Building modules, stage 2. MODPOST 94 modules WARNING: "hweight32" [fs/ntfs/ntfs.ko] undefined! WARNING: "hweight16" [drivers/input/joystick/analog.ko] undefined! WARNING: "hweight8" [drivers/input/joystick/analog.ko] undefined! make[1]: *** [__modpost] Error 1 make: *** [modules] Error 2 Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] remove carta_random32

2006-10-17T15:18:43Z

This library function should be in obj-y and not in lib-y. But when we do that it clashes unpleasantly with the assembly-language implementation in the ia64 architecture. Instead of trying to fix it all up, just remove the generic carta_random32 in the expectation that the recently-made-generic random32() will suffice. If/when perfmon is migrated to random32, ia64's private carta_random32 implementation can also be removed. Cc: Stephane Eranian Cc: "Luck, Tony" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] rename net_random to random32

2006-10-17T15:18:43Z

Make net_random() more widely available by calling it random32 akpm: hopefully this will permit the removal of carta_random32. That needs confirmation from Stephane - this code looks somewhat more computationally expensive, and has a different (ie: callee-stateful) interface. [akpm@osdl.org: lots of build fixes, cleanups] Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller Cc: Stephane Eranian Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] Add carta_random32() library routine

2006-10-11T18:14:21Z

This is a follow-up patch based on the review for perfmon2. This patch adds the carta_random32() library routine + carta_random32.h header file. This is fast, simple, and efficient pseudo number generator algorithm. We use it in perfmon2 to randomize the sampling periods. In this context, we do not need any fancy randomizer. Signed-off-by: stephane eranian Cc: David Mosberger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

IRQ: Maintain regs pointer globally rather than passing to IRQ handlers

2006-10-05T14:10:12Z

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 (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)