On Thu, May 23, 2013 at 02:24:55PM +0900, HATAYAMA Daisuke wrote: > Currently, read to /proc/vmcore is done by read_oldmem() that uses > ioremap/iounmap per a single page. For example, if memory is 1GB, > ioremap/iounmap is called (1GB / 4KB)-times, that is, 262144 > times. This causes big performance degradation due to repeated page > table changes, TLB flush and build-up of VM related objects. > > To address the issue, this patch implements mmap() on /proc/vmcore to > improve read performance under sufficiently large mapping size. > > In particular, the current main user of this mmap() is makedumpfile, > which not only reads memory from /proc/vmcore but also does other > processing like filtering, compression and I/O work. > Thanks hatayam, Thanks for the patches. This series looks good to me. I think we just need an ack from mm folks on patch 5 which introduces remap_vmalloc_range_partial(). Thanks Vivek > Benchmark > ========= > > You can see two benchmarks on terabyte memory system. Both show about > 40 seconds on 2TB system. This is almost equal to performance by > experimental kernel-side memory filtering. > > - makedumpfile mmap() benchmark, by Jingbai Ma > https://lkml.org/lkml/2013/3/27/19 > > - makedumpfile: benchmark on mmap() with /proc/vmcore on 2TB memory system > https://lkml.org/lkml/2013/3/26/914 > > ChangeLog > ========= > > v7 => v8) > > - Unify set_vmcore_list_offsets_elf{64,32} as set_vmcore_list_offsets. > [Patch 2/9] > - Introduce update_note_header_size_elf{64,32} and cleanup > get_note_number_and_size_elf{64,32} and copy_notes_elf{64,32}. > [Patch 6/9] > - Create new patch that sets VM_USERMAP flag in VM object for ELF note > segment buffer. > [Patch 7/9] > - Unify get_vmcore_size_elf{64,32} as get_vmcore_size. > [Patch 8/9] > > v6 => v7) > > - Rebase 3.10-rc2. > - Move roundup operation to note segment from patch 2/8 to patch 6/8. > - Rewrite get_note_number_and_size_elf{64,32} and > copy_notes_elf{64,32} in patch 6/8. > > v5 => v6) > > - Change patch order: clenaup patch => PT_LOAD change patch => > vmalloc-related patch => mmap patch. > - Some cleanups: improve symbol names simply, add helper functoins for > processing ELF note segment and add comments for the helper > functions. > - Fix patch description of patch 7/8. > > v4 => v5) > > - Rebase 3.10-rc1. > - Introduce remap_vmalloc_range_partial() in order to remap vmalloc > memory in a part of vma area. > - Allocate buffer for ELF note segment at 2nd kernel by vmalloc(). Use > remap_vmalloc_range_partial() to remap the memory to userspace. > > v3 => v4) > > - Rebase 3.9-rc7. > - Drop clean-up patches orthogonal to the main topic of this patch set. > - Copy ELF note segments in the 2nd kernel just as in v1. Allocate > vmcore objects per pages. => See [PATCH 5/8] > - Map memory referenced by PT_LOAD entry directly even if the start or > end of the region doesn't fit inside page boundary, no longer copy > them as the previous v3. Then, holes, outside OS memory, are visible > from /proc/vmcore. => See [PATCH 7/8] > > v2 => v3) > > - Rebase 3.9-rc3. > - Copy program headers separately from e_phoff in ELF note segment > buffer. Now there's no risk to allocate huge memory if program > header table positions after memory segment. > - Add cleanup patch that removes unnecessary variable. > - Fix wrongly using the variable that is buffer size configurable at > runtime. Instead, use the variable that has original buffer size. > > v1 => v2) > > - Clean up the existing codes: use e_phoff, and remove the assumption > on PT_NOTE entries. > - Fix potential bug that ELF header size is not included in exported > vmcoreinfo size. > - Divide patch modifying read_vmcore() into two: clean-up and primary > code change. > - Put ELF note segments in page-size boundary on the 1st kernel > instead of copying them into the buffer on the 2nd kernel. > > Test > ==== > > This patch set is composed based on v3.10-rc2, tested on x86_64, > x86_32 both with 1GB and with 5GB (over 4GB) memory configurations. > > --- > > HATAYAMA Daisuke (9): > vmcore: support mmap() on /proc/vmcore > vmcore: calculate vmcore file size from buffer size and total size of vmcore objects > vmcore: Allow user process to remap ELF note segment buffer > vmcore: allocate ELF note segment in the 2nd kernel vmalloc memory > vmalloc: introduce remap_vmalloc_range_partial > vmalloc: make find_vm_area check in range > vmcore: treat memory chunks referenced by PT_LOAD program header entries in page-size boundary in vmcore_list > vmcore: allocate buffer for ELF headers on page-size alignment > vmcore: clean up read_vmcore() > > > fs/proc/vmcore.c | 657 +++++++++++++++++++++++++++++++++-------------- > include/linux/vmalloc.h | 4 > mm/vmalloc.c | 65 +++-- > 3 files changed, 515 insertions(+), 211 deletions(-) > > -- > > Thanks. > HATAYAMA, Daisuke -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>