Revision 01599fca6758d2cd133e78f87426fc851c9ea725 authored by Andrew Morton on 13 April 2009, 17:27:49 UTC, committed by Linus Torvalds on 13 April 2009, 18:09:46 UTC
Atttempting to rid us of the problematic work_on_cpu(). Just use smp_call_fuction_single() here. This repairs a 10% sysbench(oltp)+mysql regression which Mike reported, due to commit 6b44003e5ca66a3fffeb5bc90f40ada2c4340896 Author: Andrew Morton <akpm@linux-foundation.org> Date: Thu Apr 9 09:50:37 2009 -0600 work_on_cpu(): rewrite it to create a kernel thread on demand It seems that the kernel calls these acpi-cpufreq functions at a quite high frequency. Valdis Kletnieks also reports that this causes 70-90 forks per second on his hardware. Cc: Valdis.Kletnieks@vt.edu Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Len Brown <len.brown@intel.com> Cc: Zhao Yakui <yakui.zhao@intel.com> Acked-by: Dave Jones <davej@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Tested-by: Mike Galbraith <efault@gmx.de> Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Ingo Molnar <mingo@elte.hu> [ Made it use smp_call_function_many() instead of looping over cpu's with smp_call_function_single() - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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libcrc32c.c
/*
* CRC32C
*@Article{castagnoli-crc,
* author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
* title = {{Optimization of Cyclic Redundancy-Check Codes with 24
* and 32 Parity Bits}},
* journal = IEEE Transactions on Communication,
* year = {1993},
* volume = {41},
* number = {6},
* pages = {},
* month = {June},
*}
* Used by the iSCSI driver, possibly others, and derived from the
* the iscsi-crc.c module of the linux-iscsi driver at
* http://linux-iscsi.sourceforge.net.
*
* Following the example of lib/crc32, this function is intended to be
* flexible and useful for all users. Modules that currently have their
* own crc32c, but hopefully may be able to use this one are:
* net/sctp (please add all your doco to here if you change to
* use this one!)
* <endoflist>
*
* Copyright (c) 2004 Cisco Systems, Inc.
*
* 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.
*
*/
#include <crypto/hash.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
static struct crypto_shash *tfm;
u32 crc32c(u32 crc, const void *address, unsigned int length)
{
struct {
struct shash_desc shash;
char ctx[crypto_shash_descsize(tfm)];
} desc;
int err;
desc.shash.tfm = tfm;
desc.shash.flags = 0;
*(u32 *)desc.ctx = crc;
err = crypto_shash_update(&desc.shash, address, length);
BUG_ON(err);
return *(u32 *)desc.ctx;
}
EXPORT_SYMBOL(crc32c);
static int __init libcrc32c_mod_init(void)
{
tfm = crypto_alloc_shash("crc32c", 0, 0);
if (IS_ERR(tfm))
return PTR_ERR(tfm);
return 0;
}
static void __exit libcrc32c_mod_fini(void)
{
crypto_free_shash(tfm);
}
module_init(libcrc32c_mod_init);
module_exit(libcrc32c_mod_fini);
MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
MODULE_LICENSE("GPL");
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