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

David Rientjes
2011-02-20T01:51:09Z

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 ).

> +
> +/* 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.

> + 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.

> + 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.

> +{
> + 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?

> + (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.

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.

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