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Date: Mon, 30 Jun 2008 09:16:51 +0530 From: Balbir Singh <balbir@...ux.vnet.ibm.com> To: Paul Menage <menage@...gle.com> CC: Andrew Morton <akpm@...ux-foundation.org>, YAMAMOTO Takashi <yamamoto@...inux.co.jp>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Subject: Re: [RFC 3/5] Replacement policy on heap overfull Paul Menage wrote: > On Fri, Jun 27, 2008 at 8:18 AM, Balbir Singh <balbir@...ux.vnet.ibm.com> wrote: >> >> This patch adds a policy parameter to heap_insert. While inserting an element >> if the heap is full, the policy determines which element to replace. >> The default earlier is now obtained by passing the policy as HEAP_REP_TOP. >> The new HEAP_REP_LEAF policy, replaces a leaf node (the last element). >> >> Signed-off-by: Balbir Singh <balbir@...ux.vnet.ibm.com> >> --- >> >> include/linux/prio_heap.h | 9 ++++++++- >> kernel/cgroup.c | 2 +- >> lib/prio_heap.c | 31 +++++++++++++++++++++++-------- >> 3 files changed, 32 insertions(+), 10 deletions(-) >> >> diff -puN include/linux/prio_heap.h~prio_heap_replace_leaf include/linux/prio_heap.h >> --- linux-2.6.26-rc5/include/linux/prio_heap.h~prio_heap_replace_leaf 2008-06-27 20:43:09.000000000 +0530 >> +++ linux-2.6.26-rc5-balbir/include/linux/prio_heap.h 2008-06-27 20:43:09.000000000 +0530 >> @@ -22,6 +22,11 @@ struct ptr_heap { >> int (*gt)(void *, void *); >> }; >> >> +enum heap_replacement_policy { >> + HEAP_REP_LEAF, >> + HEAP_REP_TOP, >> +}; > > Maybe "drop" rather than "replace"? HEAP_REP_TOP doesn't replace the > top element if you insert a new higher element, it drops the top. > > How about HEAP_DROP_LEAF and HEAP_DROP_MAX? You could also provide a > HEAP_DROP_MIN with the caveat that it would take linear time. > > Add comments here about what these mean? > Sure, will do >> + if (policy == HEAP_REP_TOP) > > switch() here? > Can switch over >> + if (heap->gt(p, ptrs[0])) >> + return p; >> + >> + if (policy == HEAP_REP_LEAF) { >> + /* Heap insertion */ >> + int pos = heap->size - 1; >> + res = ptrs[pos]; >> + heap_insert_at(heap, p, pos); >> + return res; >> + } >> >> /* Replace the current max and heapify */ >> res = ptrs[0]; > > This should probably be in the arm dealing with > HEAP_REP_TOP/HEAP_DROP_MAX since we only get here in that case. I can do that, I'll need to rearrange the code and merge the condition above with the ->gt check into HEAP_DROP_MAX -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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