Message-ID: <4D928682.8010100@sgi.com>
Date:	Tue, 29 Mar 2011 18:25:22 -0700
From:	Mike Travis <travis@....com>
To:	akpm@...ux-foundation.org
Cc:	LKML <linux-kernel@...r.kernel.org>, andy.shevchenko@...il.com,
	lee.schermerhorn@...com, steiner@....com, tglx@...utronix.de
Subject: Re: + bitmap-irq-add-smp_affinity_list-interface-to-proc-irq.patch
 added to -mm tree

Thanks Andrew!

Btw, I got the comment wrong, I needed one more 00000000,
[wonder who will notice? ;-)]

akpm@...ux-foundation.org wrote:
> The patch titled
>      bitmap, irq: add smp_affinity_list interface to /proc/irq
> has been added to the -mm tree.  Its filename is
>      bitmap-irq-add-smp_affinity_list-interface-to-proc-irq.patch
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
> 
> See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
> out what to do about this
> 
> The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
> 
> ------------------------------------------------------
> Subject: bitmap, irq: add smp_affinity_list interface to /proc/irq
> From: Mike Travis <travis@....com>
> 
> Manually adjusting the smp_affinity for IRQ's becomes unwieldy when the
> cpu count is large.
> 
> Setting smp affinity to cpus 256 to 263 would be:
> 
> 	echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity
> 
> instead of:
> 
> 	echo 256-263 > smp_affinity_list
> 
> Think about what it looks like for cpus around say, 4088 to 4095.
> 
> We already have many alternate "list" interfaces:
> 
> /sys/devices/system/cpu/cpuX/indexY/shared_cpu_list
> /sys/devices/system/cpu/cpuX/topology/thread_siblings_list
> /sys/devices/system/cpu/cpuX/topology/core_siblings_list
> /sys/devices/system/node/nodeX/cpulist
> /sys/devices/pci***/***/local_cpulist
> 
> 
> Add a companion interface, smp_affinity_list to use cpu lists instead of
> cpu maps.  This conforms to other companion interfaces where both a map
> and a list interface exists.
> 
> This required adding a bitmap_parselist_user() function in a manner
> similar to the bitmap_parse_user() function.
> 
> Signed-off-by: Mike Travis <travis@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Jack Steiner <steiner@....com>
> Cc: Lee Schermerhorn <lee.schermerhorn@...com>
> Cc: Andy Shevchenko <andy.shevchenko@...il.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
> 
>  Documentation/IRQ-affinity.txt     |   19 +++-
>  Documentation/filesystems/proc.txt |   11 ++
>  include/linux/bitmap.h             |    5 -
>  include/linux/cpumask.h            |   15 +++
>  kernel/irq/proc.c                  |   54 ++++++++++++-
>  lib/bitmap.c                       |  109 ++++++++++++++++++++++++---
>  6 files changed, 190 insertions(+), 23 deletions(-)
> 
> diff -puN Documentation/IRQ-affinity.txt~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq Documentation/IRQ-affinity.txt
> --- a/Documentation/IRQ-affinity.txt~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq
> +++ a/Documentation/IRQ-affinity.txt
> @@ -4,10 +4,11 @@ ChangeLog:
>  
>  SMP IRQ affinity
>  
> -/proc/irq/IRQ#/smp_affinity specifies which target CPUs are permitted
> -for a given IRQ source. It's a bitmask of allowed CPUs. It's not allowed
> -to turn off all CPUs, and if an IRQ controller does not support IRQ
> -affinity then the value will not change from the default 0xffffffff.
> +/proc/irq/IRQ#/smp_affinity and /proc/irq/IRQ#/smp_affinity_list specify
> +which target CPUs are permitted for a given IRQ source.  It's a bitmask
> +(smp_affinity) or cpu list (smp_affinity_list) of allowed CPUs.  It's not
> +allowed to turn off all CPUs, and if an IRQ controller does not support
> +IRQ affinity then the value will not change from the default of all cpus.
>  
>  /proc/irq/default_smp_affinity specifies default affinity mask that applies
>  to all non-active IRQs. Once IRQ is allocated/activated its affinity bitmask
> @@ -54,3 +55,13 @@ round-trip min/avg/max = 0.1/0.5/585.4 m
>  This time around IRQ44 was delivered only to the last four processors.
>  i.e counters for the CPU0-3 did not change.
>  
> +Here is an example of limiting that same irq (44) to cpus 1024 to 1031:
> +
> +[root@...n 44]# echo 1024-1031 > smp_affinity
> +[root@...n 44]# cat smp_affinity
> +1024-1031
> +
> +Note that to do this with a bitmask would require 32 bitmasks of zero
> +to follow the pertinent one.
> +
> +
> diff -puN Documentation/filesystems/proc.txt~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq Documentation/filesystems/proc.txt
> --- a/Documentation/filesystems/proc.txt~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq
> +++ a/Documentation/filesystems/proc.txt
> @@ -574,6 +574,12 @@ The contents of each smp_affinity file i
>    > cat /proc/irq/0/smp_affinity
>    ffffffff
>  
> +There is an alternate interface, smp_affinity_list which allows specifying
> +a cpu range instead of a bitmask:
> +
> +  > cat /proc/irq/0/smp_affinity_list
> +  1024-1031
> +
>  The default_smp_affinity mask applies to all non-active IRQs, which are the
>  IRQs which have not yet been allocated/activated, and hence which lack a
>  /proc/irq/[0-9]* directory.
> @@ -583,12 +589,13 @@ reports itself as being attached. This h
>  include information about any possible driver locality preference.
>  
>  prof_cpu_mask specifies which CPUs are to be profiled by the system wide
> -profiler. Default value is ffffffff (all cpus).
> +profiler. Default value is ffffffff (all cpus if there are only 32 of them).
>  
>  The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
>  between all the CPUs which are allowed to handle it. As usual the kernel has
>  more info than you and does a better job than you, so the defaults are the
> -best choice for almost everyone.
> +best choice for almost everyone.  [Note this applies only to those IO-APIC's
> +that support "Round Robin" interrupt distribution.]
>  
>  There are  three  more  important subdirectories in /proc: net, scsi, and sys.
>  The general  rule  is  that  the  contents,  or  even  the  existence of these
> diff -puN include/linux/bitmap.h~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq include/linux/bitmap.h
> --- a/include/linux/bitmap.h~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq
> +++ a/include/linux/bitmap.h
> @@ -55,7 +55,8 @@
>   * bitmap_parse(buf, buflen, dst, nbits)	Parse bitmap dst from kernel buf
>   * bitmap_parse_user(ubuf, ulen, dst, nbits)	Parse bitmap dst from user buf
>   * bitmap_scnlistprintf(buf, len, src, nbits)	Print bitmap src as list to buf
> - * bitmap_parselist(buf, dst, nbits)		Parse bitmap dst from list
> + * bitmap_parselist(buf, dst, nbits)		Parse bitmap dst from kernel buf
> + * bitmap_parselist_user(buf, dst, nbits)	Parse bitmap dst from user buf
>   * bitmap_find_free_region(bitmap, bits, order)	Find and allocate bit region
>   * bitmap_release_region(bitmap, pos, order)	Free specified bit region
>   * bitmap_allocate_region(bitmap, pos, order)	Allocate specified bit region
> @@ -129,6 +130,8 @@ extern int bitmap_scnlistprintf(char *bu
>  			const unsigned long *src, int nbits);
>  extern int bitmap_parselist(const char *buf, unsigned long *maskp,
>  			int nmaskbits);
> +extern int bitmap_parselist_user(const char __user *ubuf, unsigned int ulen,
> +			unsigned long *dst, int nbits);
>  extern void bitmap_remap(unsigned long *dst, const unsigned long *src,
>  		const unsigned long *old, const unsigned long *new, int bits);
>  extern int bitmap_bitremap(int oldbit,
> diff -puN include/linux/cpumask.h~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq include/linux/cpumask.h
> --- a/include/linux/cpumask.h~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq
> +++ a/include/linux/cpumask.h
> @@ -547,6 +547,21 @@ static inline int cpumask_parse_user(con
>  }
>  
>  /**
> + * cpumask_parselist_user - extract a cpumask from a user string
> + * @buf: the buffer to extract from
> + * @len: the length of the buffer
> + * @dstp: the cpumask to set.
> + *
> + * Returns -errno, or 0 for success.
> + */
> +static inline int cpumask_parselist_user(const char __user *buf, int len,
> +				     struct cpumask *dstp)
> +{
> +	return bitmap_parselist_user(buf, len, cpumask_bits(dstp),
> +							nr_cpumask_bits);
> +}
> +
> +/**
>   * cpulist_scnprintf - print a cpumask into a string as comma-separated list
>   * @buf: the buffer to sprintf into
>   * @len: the length of the buffer
> diff -puN kernel/irq/proc.c~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq kernel/irq/proc.c
> --- a/kernel/irq/proc.c~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq
> +++ a/kernel/irq/proc.c
> @@ -19,7 +19,7 @@ static struct proc_dir_entry *root_irq_d
>  
>  #ifdef CONFIG_SMP
>  
> -static int irq_affinity_proc_show(struct seq_file *m, void *v)
> +static int show_irq_affinity(int type, struct seq_file *m, void *v)
>  {
>  	struct irq_desc *desc = irq_to_desc((long)m->private);
>  	const struct cpumask *mask = desc->irq_data.affinity;
> @@ -28,7 +28,10 @@ static int irq_affinity_proc_show(struct
>  	if (irqd_is_setaffinity_pending(&desc->irq_data))
>  		mask = desc->pending_mask;
>  #endif
> -	seq_cpumask(m, mask);
> +	if (type)
> +		seq_cpumask_list(m, mask);
> +	else
> +		seq_cpumask(m, mask);
>  	seq_putc(m, '\n');
>  	return 0;
>  }
> @@ -59,7 +62,18 @@ static int irq_affinity_hint_proc_show(s
>  #endif
>  
>  int no_irq_affinity;
> -static ssize_t irq_affinity_proc_write(struct file *file,
> +static int irq_affinity_proc_show(struct seq_file *m, void *v)
> +{
> +	return show_irq_affinity(0, m, v);
> +}
> +
> +static int irq_affinity_list_proc_show(struct seq_file *m, void *v)
> +{
> +	return show_irq_affinity(1, m, v);
> +}
> +
> +
> +static ssize_t write_irq_affinity(int type, struct file *file,
>  		const char __user *buffer, size_t count, loff_t *pos)
>  {
>  	unsigned int irq = (int)(long)PDE(file->f_path.dentry->d_inode)->data;
> @@ -72,7 +86,10 @@ static ssize_t irq_affinity_proc_write(s
>  	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
>  		return -ENOMEM;
>  
> -	err = cpumask_parse_user(buffer, count, new_value);
> +	if (type)
> +		err = cpumask_parselist_user(buffer, count, new_value);
> +	else
> +		err = cpumask_parse_user(buffer, count, new_value);
>  	if (err)
>  		goto free_cpumask;
>  
> @@ -100,11 +117,28 @@ free_cpumask:
>  	return err;
>  }
>  
> +static ssize_t irq_affinity_proc_write(struct file *file,
> +		const char __user *buffer, size_t count, loff_t *pos)
> +{
> +	return write_irq_affinity(0, file, buffer, count, pos);
> +}
> +
> +static ssize_t irq_affinity_list_proc_write(struct file *file,
> +		const char __user *buffer, size_t count, loff_t *pos)
> +{
> +	return write_irq_affinity(1, file, buffer, count, pos);
> +}
> +
>  static int irq_affinity_proc_open(struct inode *inode, struct file *file)
>  {
>  	return single_open(file, irq_affinity_proc_show, PDE(inode)->data);
>  }
>  
> +static int irq_affinity_list_proc_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, irq_affinity_list_proc_show, PDE(inode)->data);
> +}
> +
>  static int irq_affinity_hint_proc_open(struct inode *inode, struct file *file)
>  {
>  	return single_open(file, irq_affinity_hint_proc_show, PDE(inode)->data);
> @@ -125,6 +159,14 @@ static const struct file_operations irq_
>  	.release	= single_release,
>  };
>  
> +static const struct file_operations irq_affinity_list_proc_fops = {
> +	.open		= irq_affinity_list_proc_open,
> +	.read		= seq_read,
> +	.llseek		= seq_lseek,
> +	.release	= single_release,
> +	.write		= irq_affinity_list_proc_write,
> +};
> +
>  static int default_affinity_show(struct seq_file *m, void *v)
>  {
>  	seq_cpumask(m, irq_default_affinity);
> @@ -289,6 +331,10 @@ void register_irq_proc(unsigned int irq,
>  	proc_create_data("affinity_hint", 0400, desc->dir,
>  			 &irq_affinity_hint_proc_fops, (void *)(long)irq);
>  
> +	/* create /proc/irq/<irq>/smp_affinity_list */
> +	proc_create_data("smp_affinity_list", 0600, desc->dir,
> +			 &irq_affinity_list_proc_fops, (void *)(long)irq);
> +
>  	proc_create_data("node", 0444, desc->dir,
>  			 &irq_node_proc_fops, (void *)(long)irq);
>  #endif
> diff -puN lib/bitmap.c~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq lib/bitmap.c
> --- a/lib/bitmap.c~bitmap-irq-add-smp_affinity_list-interface-to-proc-irq
> +++ a/lib/bitmap.c
> @@ -571,8 +571,11 @@ int bitmap_scnlistprintf(char *buf, unsi
>  EXPORT_SYMBOL(bitmap_scnlistprintf);
>  
>  /**
> - * bitmap_parselist - convert list format ASCII string to bitmap
> + * __bitmap_parselist - convert list format ASCII string to bitmap
>   * @bp: read nul-terminated user string from this buffer
> + * @buflen: buffer size in bytes.  If string is smaller than this
> + *    then it must be terminated with a \0.
> + * @is_user: location of buffer, 0 indicates kernel space
>   * @maskp: write resulting mask here
>   * @nmaskbits: number of bits in mask to be written
>   *
> @@ -587,20 +590,63 @@ EXPORT_SYMBOL(bitmap_scnlistprintf);
>   *    %-EINVAL: invalid character in string
>   *    %-ERANGE: bit number specified too large for mask
>   */
> -int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
> +int __bitmap_parselist(const char *buf, unsigned int buflen,
> +		int is_user, unsigned long *maskp,
> +		int nmaskbits)
>  {
>  	unsigned a, b;
> +	int c, old_c, totaldigits;
> +	const char __user *ubuf = buf;
> +	int exp_digit, in_range;
>  
> +	totaldigits = c = 0;
>  	bitmap_zero(maskp, nmaskbits);
>  	do {
> -		if (!isdigit(*bp))
> -			return -EINVAL;
> -		b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
> -		if (*bp == '-') {
> -			bp++;
> -			if (!isdigit(*bp))
> +		exp_digit = 1;
> +		in_range = 0;
> +		a = b = 0;
> +
> +		/* Get the next cpu# or a range of cpu#'s */
> +		while (buflen) {
> +			old_c = c;
> +			if (is_user) {
> +				if (__get_user(c, ubuf++))
> +					return -EFAULT;
> +			} else
> +				c = *buf++;
> +			buflen--;
> +			if (isspace(c))
> +				continue;
> +
> +			/*
> +			 * If the last character was a space and the current
> +			 * character isn't '\0', we've got embedded whitespace.
> +			 * This is a no-no, so throw an error.
> +			 */
> +			if (totaldigits && c && isspace(old_c))
> +				return -EINVAL;
> +
> +			/* A '\0' or a ',' signal the end of a cpu# or range */
> +			if (c == '\0' || c == ',')
> +				break;
> +
> +			if (c == '-') {
> +				if (exp_digit || in_range)
> +					return -EINVAL;
> +				b = 0;
> +				in_range = 1;
> +				exp_digit = 1;
> +				continue;
> +			}
> +
> +			if (!isdigit(c))
>  				return -EINVAL;
> -			b = simple_strtoul(bp, (char **)&bp, BASEDEC);
> +
> +			b = b * 10 + (c - '0');
> +			if (!in_range)
> +				a = b;
> +			exp_digit = 0;
> +			totaldigits++;
>  		}
>  		if (!(a <= b))
>  			return -EINVAL;
> @@ -610,13 +656,52 @@ int bitmap_parselist(const char *bp, uns
>  			set_bit(a, maskp);
>  			a++;
>  		}
> -		if (*bp == ',')
> -			bp++;
> -	} while (*bp != '\0' && *bp != '\n');
> +	} while (buflen && c == ',');
>  	return 0;
>  }
> +
> +int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
> +{
> +	char *nl  = strchr(bp, '\n');
> +	int len;
> +
> +	if (nl)
> +		len = nl - bp;
> +	else
> +		len = strlen(bp);
> +
> +	return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
> +}
>  EXPORT_SYMBOL(bitmap_parselist);
>  
> +
> +/**
> + * bitmap_parselist_user()
> + *
> + * @ubuf: pointer to user buffer containing string.
> + * @ulen: buffer size in bytes.  If string is smaller than this
> + *    then it must be terminated with a \0.
> + * @maskp: pointer to bitmap array that will contain result.
> + * @nmaskbits: size of bitmap, in bits.
> + *
> + * Wrapper for bitmap_parselist(), providing it with user buffer.
> + *
> + * We cannot have this as an inline function in bitmap.h because it needs
> + * linux/uaccess.h to get the access_ok() declaration and this causes
> + * cyclic dependencies.
> + */
> +int bitmap_parselist_user(const char __user *ubuf,
> +			unsigned int ulen, unsigned long *maskp,
> +			int nmaskbits)
> +{
> +	if (!access_ok(VERIFY_READ, ubuf, ulen))
> +		return -EFAULT;
> +	return __bitmap_parselist((const char *)ubuf,
> +					ulen, 1, maskp, nmaskbits);
> +}
> +EXPORT_SYMBOL(bitmap_parselist_user);
> +
> +
>  /**
>   * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
>   *	@buf: pointer to a bitmap
> _
> 
> Patches currently in -mm which might be from travis@....com are
> 
> bitmap-irq-add-smp_affinity_list-interface-to-proc-irq.patch
> 
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