Re: [PATCH 2/6] x86: Minimize initial e820 messages

[Mike Travis <travis@sgi.com>]

David Rientjes wrote:
> On Fri, 18 Feb 2011, Mike Travis wrote:
> 
>> Minimize the early e820 messages by printing less characters
>> for the address range as well as abbreviating the type info
>> for each entry.
>>
>> Also the "modified physical RAM map" was mostly a duplicate of
>> the original e820 memory map printout.  Minimize the output
>> by only printing those entries that were actually modified.
>>
>> v1: Added pertinent __init & __initdata specifiers
>>     Changed some inlines to __init functions to avoid the
>>     the compiler un-inlining them into the wrong section.
>>
>> v2: updated to apply to x86-tip
>>
>> Signed-off-by: Mike Travis <travis@sgi.com>
>> Reviewed-by: Jack Steiner <steiner@sgi.com>
>> Reviewed-by: Robin Holt <holt@sgi.com>
>> ---
>>  arch/x86/kernel/e820.c      |  138 +++++++++++++++++++++++++++-----------------
>>  arch/x86/platform/efi/efi.c |   10 +--
>>  2 files changed, 91 insertions(+), 57 deletions(-)
>>
>> --- linux.orig/arch/x86/kernel/e820.c
>> +++ linux/arch/x86/kernel/e820.c
>> @@ -39,6 +39,13 @@
>>  struct e820map e820;
>>  struct e820map e820_saved;
>>  
>> +/*
>> + * Keep track of previous e820 mappings so we can reduce the number
>> + * of messages when printing the "modified" e820 map
>> + */
>> +static struct e820map e820_prev __initdata;
>> +static int e820_prev_saved __initdata;
> 
> bool?
> 
>> +
>>  /* For PCI or other memory-mapped resources */
>>  unsigned long pci_mem_start = 0xaeedbabe;
>>  #ifdef CONFIG_PCI
>> @@ -125,42 +132,85 @@ void __init e820_add_region(u64 start, u
>>  	__e820_add_region(&e820, start, size, type);
>>  }
>>  
>> -static void __init e820_print_type(u32 type)
>> +/* long description */
>> +static const char * __init e820_type_to_string(int e820_type)
>> +{
>> +	switch (e820_type) {
>> +	case E820_RESERVED_KERN:	return "Kernel RAM";
>> +	case E820_RAM:	return "System RAM";
>> +	case E820_ACPI:	return "ACPI Tables";
>> +	case E820_NVS:	return "ACPI Non-Volatile Storage";
>> +	case E820_UNUSABLE:	return "Unusable Memory";
>> +	default:	return "Reserved";
>> +	}
>> +}
> 
> All of the callers of this function would probably benefit from 
> surrounding each return string with ( and ).

Good point, thanks.
> 
>> +
>> +/* short description, saves log space when there are 100's of e820 entries */
>> +static char * __init e820_types(int e820_type)
>>  {
>> -	switch (type) {
>> -	case E820_RAM:
>> -	case E820_RESERVED_KERN:
>> -		printk(KERN_CONT "(usable)");
>> -		break;
>> -	case E820_RESERVED:
>> -		printk(KERN_CONT "(reserved)");
>> -		break;
>> -	case E820_ACPI:
>> -		printk(KERN_CONT "(ACPI data)");
>> -		break;
>> -	case E820_NVS:
>> -		printk(KERN_CONT "(ACPI NVS)");
>> -		break;
>> -	case E820_UNUSABLE:
>> -		printk(KERN_CONT "(unusable)");
>> -		break;
>> -	default:
>> -		printk(KERN_CONT "type %u", type);
>> -		break;
>> +	switch (e820_type) {
>> +	case E820_RESERVED_KERN:	return "KRAM";
>> +	case E820_RAM:	return "SRAM";
> 
> Using the abbreviation "SRAM" for "system RAM" is just going to lead to 
> confusion.

Suggestions?

> 
>> +	case E820_ACPI:	return "ACPI";
>> +	case E820_NVS:	return "NVS";
>> +	case E820_UNUSABLE:	return "UM";
> 
> I know these are intended to be very short, but nobody is going to 
> conclude that "UM" means unusuable memory.

UM, what do you think it should be?  ;-)

> 
>> +	default:	return "RESVD";
>>  	}
>>  }
>>  
>> +static void __init e820_print_header(void)
>> +{
>> +	pr_info("types: %s=(%s) %s=(%s) %s=(%s) %s=(%s) %s=(%s) %s=(%s)\n",
>> +		e820_types(E820_RESERVED_KERN),
>> +				e820_type_to_string(E820_RESERVED_KERN),
>> +		e820_types(E820_RAM), e820_type_to_string(E820_RAM),
>> +		e820_types(E820_RESERVED), e820_type_to_string(E820_RESERVED),
>> +		e820_types(E820_ACPI), e820_type_to_string(E820_ACPI),
>> +		e820_types(E820_NVS), e820_type_to_string(E820_NVS),
>> +		e820_types(E820_UNUSABLE), e820_type_to_string(E820_UNUSABLE));
>> +}
>> +
>> +/* compare new entry with old so we only print "modified" entries */
>> +static int __init not_modified(int i, int j)
> 
> I know it's static, but this needs a better function name.  I hope it's 
> never passed negative actuals by mistake.

What (!not) doesn't make sense? ;-)

> 
>> +{
>> +	for (; j < e820_prev.nr_map &&
>> +		e820_prev.map[j].addr <= e820.map[i].addr; j++) {
>> +
>> +		if (e820.map[i].addr == e820_prev.map[j].addr &&
>> +		    e820.map[i].size == e820_prev.map[j].size &&
>> +		    e820.map[i].type == e820_prev.map[j].type)
>> +			return j;
>> +	}
>> +	return 0;
>> +}
>> +
>>  void __init e820_print_map(char *who)
>>  {
>> -	int i;
>> +	int i, j = 0;
>> +	int hdr = 0;
>> +	int mod = strcmp(who, "modified") == 0;
> 
> bool?
> 
>>  
>>  	for (i = 0; i < e820.nr_map; i++) {
>> -		printk(KERN_INFO " %s: %016Lx - %016Lx ", who,
>> -		       (unsigned long long) e820.map[i].addr,
>> -		       (unsigned long long)
>> -		       (e820.map[i].addr + e820.map[i].size));
>> -		e820_print_type(e820.map[i].type);
>> -		printk(KERN_CONT "\n");
>> +		/* only print those entries that were really modified */
>> +		if (mod)
>> +			j = not_modified(i, j);
>> +
>> +		if (!j) {
>> +			if (!hdr++)
>> +				e820_print_header();
>> +
>> +			pr_info("%s: %Lx+%Lx (%s)\n", who,
> 
> We don't want a space prefix anymore?

Why would we?
> 
>> +			       (unsigned long long) e820.map[i].addr,
>> +			       (unsigned long long) e820.map[i].size,
>> +			       e820_types(e820.map[i].type));
>> +		}
>> +	}
>> +	if (!hdr)
>> +		pr_info("<none>\n");
>> +
>> +	if (!e820_prev_saved) {
>> +		memcpy(&e820_prev, &e820, sizeof(struct e820map));
>> +		e820_prev_saved = 1;
>>  	}
>>  }
>>  
>> @@ -437,13 +487,11 @@ static u64 __init __e820_update_range(st
>>  		size = ULLONG_MAX - start;
>>  
>>  	end = start + size;
>> -	printk(KERN_DEBUG "e820 update range: %016Lx - %016Lx ",
>> +	pr_debug("e820 update range: %Lx+%Lx %s ==> %s\n",
>>  		       (unsigned long long) start,
>> -		       (unsigned long long) end);
>> -	e820_print_type(old_type);
>> -	printk(KERN_CONT " ==> ");
>> -	e820_print_type(new_type);
>> -	printk(KERN_CONT "\n");
>> +		       (unsigned long long) size,
>> +			e820_type_to_string(old_type),
>> +			e820_type_to_string(new_type));
>>  
>>  	for (i = 0; i < e820x->nr_map; i++) {
>>  		struct e820entry *ei = &e820x->map[i];
>> @@ -518,12 +566,10 @@ u64 __init e820_remove_range(u64 start,
>>  		size = ULLONG_MAX - start;
>>  
>>  	end = start + size;
>> -	printk(KERN_DEBUG "e820 remove range: %016Lx - %016Lx ",
>> +	printk(KERN_DEBUG "e820 remove range: %016Lx - %016Lx %s\n",
>>  		       (unsigned long long) start,
>> -		       (unsigned long long) end);
>> -	if (checktype)
>> -		e820_print_type(old_type);
>> -	printk(KERN_CONT "\n");
>> +		       (unsigned long long) end,
>> +			checktype ? e820_type_to_string(old_type) : "");
>>  
>>  	for (i = 0; i < e820.nr_map; i++) {
>>  		struct e820entry *ei = &e820.map[i];
>> @@ -576,7 +622,7 @@ void __init update_e820(void)
>>  	if (sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &nr_map))
>>  		return;
>>  	e820.nr_map = nr_map;
>> -	printk(KERN_INFO "modified physical RAM map:\n");
>> +	printk(KERN_INFO "physical RAM map entries that were modified:\n");
>>  	e820_print_map("modified");
>>  }
>>  static void __init update_e820_saved(void)
>> @@ -926,18 +972,6 @@ void __init finish_e820_parsing(void)
>>  	}
>>  }
>>  
>> -static inline const char *e820_type_to_string(int e820_type)
>> -{
>> -	switch (e820_type) {
>> -	case E820_RESERVED_KERN:
>> -	case E820_RAM:	return "System RAM";
>> -	case E820_ACPI:	return "ACPI Tables";
>> -	case E820_NVS:	return "ACPI Non-volatile Storage";
>> -	case E820_UNUSABLE:	return "Unusable memory";
>> -	default:	return "reserved";
>> -	}
>> -}
>> -
>>  /*
>>   * Mark e820 reserved areas as busy for the resource manager.
>>   */
>> --- linux.orig/arch/x86/platform/efi/efi.c
>> +++ linux/arch/x86/platform/efi/efi.c
>> @@ -306,11 +306,11 @@ static void __init print_efi_memmap(void
>>  	     p < memmap.map_end;
>>  	     p += memmap.desc_size, i++) {
>>  		md = p;
>> -		printk(KERN_INFO PFX "mem%02u: type=%u, attr=0x%llx, "
>> -			"range=[0x%016llx-0x%016llx) (%lluMB)\n",
>> -			i, md->type, md->attribute, md->phys_addr,
>> -			md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT),
>> -			(md->num_pages >> (20 - EFI_PAGE_SHIFT)));
>> +		pr_info(PFX
>> +			"mem%u: range %llx+%llx (%lluMB) type %u attr %llx\n",
> 
> The range you're printing is now ambiguous because you're now showing the 
> length rather than the ending length (implying that what you're displaying 
> is not a range at all, but it's specified as one).  I typically don't see 
> "100+12" as describing [100,112), for example.

Again, I'm open for suggestions.  I thought that changing base-end to base+range
would be coherent?  
> 
> This is also the second time in the patchset where you're printing hex 
> values without a "0x" prefix, that can be confusing and it's not like "0x" 
> is egregiously long.  I can understand removing the zero padding, but not 
> the prefix.

The problem comes when there are zillions of them.

> 
>> +			i, md->phys_addr, md->num_pages << EFI_PAGE_SHIFT,
>> +			(md->num_pages >> (20 - EFI_PAGE_SHIFT)),
>> +			md->type, md->attribute);
>>  	}
>>  }
>>  #endif  /*  EFI_DEBUG  */