On 2014.10.27 at 21:40 +0100, Markus Trippelsdorf wrote: > On my v3.18-rc2 kernel isolate_freepages_block() sometimes shows up very > high (>20%) in perf top during the configuration phase of software > builds. It increases build time considerably. > > Unfortunately the issue is not 100% reproducible, because it appears > only intermittently. And the symptoms vanish after a few minutes. > > I think the "mm, compaction" series from Vlastimil is to blame, but it's > hard to be sure when bisection doesn't work. Here is an example: Overhead Shared Object Symbol 59.12% [kernel] [k] isolate_freepages_block 4.75% [kernel] [k] amd_e400_idle 1.10% [kernel] [k] clear_page_c 0.89% [kernel] [k] get_pfnblock_flags_mask 0.64% ld-2.19.90.so [.] do_lookup_x 0.64% [kernel] [k] unmap_single_vma 0.58% [kernel] [k] copy_page_rep 0.54% libc-2.19.90.so [.] memcpy@@GLIBC_2.14 0.52% [kernel] [k] filemap_map_pages 0.47% [kernel] [k] _cond_resched -- Markus -- 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>