Re: [patch] tune vmalloc size
From: Karsten Keil
Date: Wed Sep 15 2004 - 10:01:45 EST
On Wed, Sep 15, 2004 at 03:29:53PM +0200, Andi Kleen wrote:
> Ingo Molnar <mingo@xxxxxxx> writes:
>
> > there are a few devices that use lots of ioremap space. vmalloc space is
> > a showstopper problem for them.
> >
> > this patch adds the vmalloc=<size> boot parameter to override
> > __VMALLOC_RESERVE. The default is 128mb right now - e.g. vmalloc=256m
> > doubles the size.
>
> Ah, Karsten Keil did a similar patch some months ago. There is
> clearly a need.
>
> But I think this should be self tuning instead. For a machine with
> less than 900MB of memory the vmalloc area can be automagically increased,
> growing into otherwise unused address space.
>
> This way many users wouldn't need to specify weird options. So far
> most machines still don't have more than 512MB.
>
Yes my patch has this autotune already in.
Hmm, I though I did sent it on LKML begin on this year, but after looking
through the archives, it didn't happend.
Here is my version.
diff -urN linux-2.6.9-rc2-bk2.org/arch/i386/boot/setup.S linux-2.6.9-rc2-bk2/arch/i386/boot/setup.S
--- linux-2.6.9-rc2-bk2.org/arch/i386/boot/setup.S 2004-06-18 23:36:57.000000000 +0200
+++ linux-2.6.9-rc2-bk2/arch/i386/boot/setup.S 2004-09-15 16:50:53.760287653 +0200
@@ -156,7 +156,7 @@
# can be located anywhere in
# low memory 0x10000 or higher.
-ramdisk_max: .long (MAXMEM-1) & 0x7fffffff
+ramdisk_max: .long (__MAXMEM-1) & 0x7fffffff
# (Header version 0x0203 or later)
# The highest safe address for
# the contents of an initrd
diff -urN linux-2.6.9-rc2-bk2.org/arch/i386/kernel/setup.c linux-2.6.9-rc2-bk2/arch/i386/kernel/setup.c
--- linux-2.6.9-rc2-bk2.org/arch/i386/kernel/setup.c 2004-09-15 16:45:31.488885339 +0200
+++ linux-2.6.9-rc2-bk2/arch/i386/kernel/setup.c 2004-09-15 16:50:53.779285142 +0200
@@ -97,6 +97,11 @@
/* For PCI or other memory-mapped resources */
unsigned long pci_mem_start = 0x10000000;
+/* reserved mapping space for vmalloc and ioremap */
+unsigned long vmalloc_reserve = __VMALLOC_RESERVE_DEFAULT;
+EXPORT_SYMBOL(vmalloc_reserve);
+static unsigned long vm_reserve __initdata = -1;
+
/* user-defined highmem size */
static unsigned int highmem_pages = -1;
@@ -814,7 +819,16 @@
*/
if (c == ' ' && !memcmp(from, "highmem=", 8))
highmem_pages = memparse(from+8, &from) >> PAGE_SHIFT;
-
+
+ /*
+ * vm_reserve=size forces to reserve 'size' bytes for vmalloc and
+ * ioremap areas minimum is 32 MB maximum is 800 MB
+ * the default without vm_reserve depends on the total amount of
+ * memory the minimum default is 128 MB
+ */
+ if (c == ' ' && !memcmp(from, "vm_reserve=", 11))
+ vm_reserve = memparse(from+11, &from);
+
c = *(from++);
if (!c)
break;
@@ -1019,7 +1033,28 @@
start_pfn = PFN_UP(init_pg_tables_end);
find_max_pfn();
+
+ /*
+ * calculate the default size of vmalloc/ioremap area
+ * overwrite with the value of the vm_reserve= option
+ * if set
+ */
+ if (max_pfn >= PFN_UP(KERNEL_MAXMEM - __VMALLOC_RESERVE_DEFAULT))
+ vmalloc_reserve = __VMALLOC_RESERVE_DEFAULT;
+ else
+ vmalloc_reserve = KERNEL_MAXMEM - PFN_PHYS(max_pfn);
+ if (vm_reserve != -1) {
+ if (vm_reserve < __VMALLOC_RESERVE_MIN)
+ vm_reserve = __VMALLOC_RESERVE_MIN;
+ if (vm_reserve > __VMALLOC_RESERVE_MAX)
+ vm_reserve = __VMALLOC_RESERVE_MAX;
+ vmalloc_reserve = vm_reserve;
+ }
+
+ printk(KERN_NOTICE "%ldMB vmalloc/ioremap area available.\n",
+ vmalloc_reserve>>20);
+
max_low_pfn = find_max_low_pfn();
#ifdef CONFIG_HIGHMEM
diff -urN linux-2.6.9-rc2-bk2.org/arch/i386/mm/discontig.c linux-2.6.9-rc2-bk2/arch/i386/mm/discontig.c
--- linux-2.6.9-rc2-bk2.org/arch/i386/mm/discontig.c 2004-09-15 16:45:31.865835529 +0200
+++ linux-2.6.9-rc2-bk2/arch/i386/mm/discontig.c 2004-09-15 16:50:53.788283952 +0200
@@ -266,6 +266,19 @@
system_start_pfn = min_low_pfn = PFN_UP(init_pg_tables_end);
find_max_pfn();
+
+ /* Added 2004-03-02, <garloff@xxxxxxx>, copied from i386/setup.c
+ * but leave out automatic vmalloc size increase ... */
+ if (vm_reserve != -1) {
+ if (vm_reserve < __VMALLOC_RESERVE_MIN)
+ vm_reserve = __VMALLOC_RESERVE_MIN;
+ if (vm_reserve > __VMALLOC_RESERVE_MAX)
+ vm_reserve = __VMALLOC_RESERVE_MAX;
+ vmalloc_reserve = vm_reserve;
+ }
+ printk(KERN_NOTICE "%ldMB vmalloc/ioremap area available.\n",
+ vmalloc_reserve>>20);
+
system_max_low_pfn = max_low_pfn = find_max_low_pfn() - reserve_pages;
printk("reserve_pages = %ld find_max_low_pfn() ~ %ld\n",
reserve_pages, max_low_pfn + reserve_pages);
diff -urN linux-2.6.9-rc2-bk2.org/Documentation/kernel-parameters.txt linux-2.6.9-rc2-bk2/Documentation/kernel-parameters.txt
--- linux-2.6.9-rc2-bk2.org/Documentation/kernel-parameters.txt 2004-09-15 16:45:29.162192787 +0200
+++ linux-2.6.9-rc2-bk2/Documentation/kernel-parameters.txt 2004-09-15 16:50:53.799282498 +0200
@@ -1280,6 +1280,11 @@
This is actually a boot loader parameter; the value is
passed to the kernel using a special protocol.
+ vm_reserve=nn[KM]
+ [KNL,BOOT,IA-32] force use of a specific amount of
+ virtual memory for vmalloc and ioremap allocations
+ minimum 32 MB maximum 800 MB
+
vmhalt= [KNL,S390]
vmpoff= [KNL,S390]
diff -urN linux-2.6.9-rc2-bk2.org/include/asm-i386/page.h linux-2.6.9-rc2-bk2/include/asm-i386/page.h
--- linux-2.6.9-rc2-bk2.org/include/asm-i386/page.h 2004-09-15 16:46:01.094973092 +0200
+++ linux-2.6.9-rc2-bk2/include/asm-i386/page.h 2004-09-15 16:50:53.809281176 +0200
@@ -98,10 +98,15 @@
* This much address space is reserved for vmalloc() and iomap()
* as well as fixmap mappings.
*/
-#define __VMALLOC_RESERVE (128 << 20)
+#define __VMALLOC_RESERVE_MIN (32 << 20)
+#define __VMALLOC_RESERVE_DEFAULT (128 << 20)
+#define __VMALLOC_RESERVE_MAX (800 << 20)
+#define __RESERVED_AREA (10 << 20)
#ifndef __ASSEMBLY__
+extern unsigned long vmalloc_reserve;
+
/* Pure 2^n version of get_order */
static __inline__ int get_order(unsigned long size)
{
@@ -128,11 +133,14 @@
#define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET)
-#define VMALLOC_RESERVE ((unsigned long)__VMALLOC_RESERVE)
-#define MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE)
+#define KERNEL_MEMORY ((unsigned long)(FIXADDR_START - __PAGE_OFFSET))
+#define RESERVED_AREA ((unsigned long)__RESERVED_AREA)
+#define KERNEL_MAXMEM ((unsigned long)(KERNEL_MEMORY - RESERVED_AREA))
+#define __MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE_MAX)
+#define MAXMEM ((unsigned long)(-PAGE_OFFSET-vmalloc_reserve))
#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET)
#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
-#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
+#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
#ifndef CONFIG_DISCONTIGMEM
#define pfn_to_page(pfn) (mem_map + (pfn))
#define page_to_pfn(page) ((unsigned long)((page) - mem_map))
--
Karsten Keil
SuSE Labs
ISDN development
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