On 11/05/2013 01:22 AM, David Vrabel wrote: > On 04/11/13 12:39, Bob Liu wrote: >> Currently the goal_page in xen-selfballon doesn't consider much about pages >> used >> in kernel space. >> A typical usage is slab pages, without consider slab pages the goal_page >> result >> may be too rough and lead extra memory pressure to guest os. > > Can you provide some real world figures where the calculatation got it > wrong? What was the resultant behavior? Swap death? OOM killer? >
Sorry, I didn't run any testing I just think it's unreasonable while reading the source code. vm_memory_committed() only calculate pages which mapped to process address space, but the kernel itself(like block, fs and network subsystem) may occupy some memory. And it's possible that those subsystem may occupy a significant amount of memory in some situation. I'm afraid if we don't consider those kernel memory while calculating goal_pages, guest memory will be set lower than guest really needs. >> Signed-off-by: Bob Liu <bob....@oracle.com> >> --- >> drivers/xen/xen-selfballoon.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/xen/xen-selfballoon.c b/drivers/xen/xen-selfballoon.c >> index 21e18c1..4814759 100644 >> --- a/drivers/xen/xen-selfballoon.c >> +++ b/drivers/xen/xen-selfballoon.c >> @@ -191,6 +191,8 @@ static void selfballoon_process(struct work_struct *work) >> tgt_pages = cur_pages; /* default is no change */ >> goal_pages = vm_memory_committed() + >> totalreserve_pages + >> + global_page_state(NR_SLAB_RECLAIMABLE) + > > Does SLAB_RECLAIMABLE want to be included here? Unless I'm > misunderstanding here, SLAB_RECLAIMABLE is effectively free. > SLAB_RECLAIMABLE isn't effectively free, it means the slab page is in used but can be reclaimed(freed) during memory pressure. >> + global_page_state(NR_SLAB_UNRECLAIMABLE) + > > This bit looks fine to me. > >> MB2PAGES(selfballoon_reserved_mb); >> #ifdef CONFIG_FRONTSWAP >> /* allow space for frontswap pages to be repatriated */ > > David > Thanks for your review. -- Regards, -Bob -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
