Hello Pratysh,
>Currently we translate some of the VA areas using linear mapping while some
>other(which can not be linearly mapped) using page table.
>
>However, we will have entry of a page in the page table irrespective of its
>virtual region. So, we can always look into page table for any VA to PA
>translation. This approach will solve lot of complexity in makedumpfile. It
>will in turn remove dependency over variables like VMALLOC_START,
>MODULES_VADDR etc whose definition keeps changing in newer kernel version.
>
>Moreover, I do not see any side effect of this approach in terms of
>execution timing. I tested with IBM x3950 X6 machine having 4136359 MB of
>memory. These are the results of makedumpfile execution time:
>
>Without this patch:
>===================
>With -d 31:
>Trial 1: 237.59526248 S
>Trial 2: 235.236914962 S
>Trail 3: 237.678712045 S
>
>With -d 1:
>Trial 1: 2548.905296877 S
>Trial 2: 2549.759881756 S
>
>With this patch:
>===================
>With -d 31:
>Trial 1: 232.713841516 S
>Trial 2: 228.45697177 S
>Trail 3: 232.942262441 S
>
>With -d 1:
>Trial 1: 2768.424565806 S
>Trial 2: 2749.622115455 S
>Trail 3: 2537.770359073 S
Could you increase the number of trials ?
If the average time is close to the results of Trial 1 (2768s) and 2 (2749s),
the regression rate is 8% and it sounds neither large nor small.
If the average is a level of 2500s like Trial 3, it's ideal.
>Signed-off-by: Pratyush Anand <panand at redhat.com>
>---
> arch/x86_64.c | 42 ++++++++----------------------------------
> makedumpfile.h | 4 ++--
> 2 files changed, 10 insertions(+), 36 deletions(-)
>
>diff --git a/arch/x86_64.c b/arch/x86_64.c
>index a96fd8ae00a1..fe2764a8bec2 100644
>--- a/arch/x86_64.c
>+++ b/arch/x86_64.c
>@@ -203,6 +203,12 @@ vtop4_x86_64(unsigned long vaddr)
> {
> unsigned long page_dir, pml4, pgd_paddr, pgd_pte, pmd_paddr, pmd_pte;
> unsigned long pte_paddr, pte;
>+ unsigned long phys_base;
>+
>+ if (SYMBOL(phys_base) != NOT_FOUND_SYMBOL)
>+ phys_base = info->phys_base;
>+ else
>+ phys_base = 0;
>
> if (SYMBOL(init_level4_pgt) == NOT_FOUND_SYMBOL) {
> ERRMSG("Can't get the symbol of init_level4_pgt.\n");
>@@ -212,9 +218,9 @@ vtop4_x86_64(unsigned long vaddr)
> /*
> * Get PGD.
> */
>- page_dir = SYMBOL(init_level4_pgt);
>+ page_dir = SYMBOL(init_level4_pgt) - __START_KERNEL_map + phys_base;
I want to confirm that this VA to PA translation is always safe,
otherwise we should do the condition check which was done in
vaddr_to_paddr_x86_64(), isn't it ?
Thanks,
Atsushi Kumagai
> page_dir += pml4_index(vaddr) * sizeof(unsigned long);
>- if (!readmem(VADDR, page_dir, &pml4, sizeof pml4)) {
>+ if (!readmem(PADDR, page_dir, &pml4, sizeof pml4)) {
> ERRMSG("Can't get pml4 (page_dir:%lx).\n", page_dir);
> return NOT_PADDR;
> }
>@@ -285,38 +291,6 @@ vtop4_x86_64(unsigned long vaddr)
> return (pte & ENTRY_MASK) + PAGEOFFSET(vaddr);
> }
>
>-unsigned long long
>-vaddr_to_paddr_x86_64(unsigned long vaddr)
>-{
>- unsigned long phys_base;
>- unsigned long long paddr;
>-
>- /*
>- * Check the relocatable kernel.
>- */
>- if (SYMBOL(phys_base) != NOT_FOUND_SYMBOL)
>- phys_base = info->phys_base;
>- else
>- phys_base = 0;
>-
>- if (is_vmalloc_addr_x86_64(vaddr)) {
>- if ((paddr = vtop4_x86_64(vaddr)) == NOT_PADDR) {
>- ERRMSG("Can't convert a virtual address(%lx) to " \
>- "physical address.\n", vaddr);
>- return NOT_PADDR;
>- }
>- } else if (vaddr >= __START_KERNEL_map) {
>- paddr = vaddr - __START_KERNEL_map + phys_base;
>-
>- } else {
>- if (is_xen_memory())
>- paddr = vaddr - PAGE_OFFSET_XEN_DOM0;
>- else
>- paddr = vaddr - PAGE_OFFSET;
>- }
>- return paddr;
>-}
>-
> /*
> * for Xen extraction
> */
>diff --git a/makedumpfile.h b/makedumpfile.h
>index a5955ff750e5..13559651feb6 100644
>--- a/makedumpfile.h
>+++ b/makedumpfile.h
>@@ -863,12 +863,12 @@ int is_vmalloc_addr_x86_64(ulong vaddr);
> int get_phys_base_x86_64(void);
> int get_machdep_info_x86_64(void);
> int get_versiondep_info_x86_64(void);
>-unsigned long long vaddr_to_paddr_x86_64(unsigned long vaddr);
>+unsigned long long vtop4_x86_64(unsigned long vaddr);
> #define find_vmemmap() find_vmemmap_x86_64()
> #define get_phys_base() get_phys_base_x86_64()
> #define get_machdep_info() get_machdep_info_x86_64()
> #define get_versiondep_info() get_versiondep_info_x86_64()
>-#define vaddr_to_paddr(X) vaddr_to_paddr_x86_64(X)
>+#define vaddr_to_paddr(X) vtop4_x86_64(X)
> #define is_phys_addr(X) (!is_vmalloc_addr_x86_64(X))
> #endif /* x86_64 */
>
>--
>2.7.4
>
>
>_______________________________________________
>kexec mailing list
>kexec at lists.infradead.org
>http://lists.infradead.org/mailman/listinfo/kexec
