From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f71.google.com (mail-oi0-f71.google.com [209.85.218.71]) by kanga.kvack.org (Postfix) with ESMTP id 4383E6B0279 for ; Mon, 17 Jul 2017 05:04:56 -0400 (EDT) Received: by mail-oi0-f71.google.com with SMTP id d77so11176002oig.7 for ; Mon, 17 Jul 2017 02:04:56 -0700 (PDT) Received: from sender-pp-092.zoho.com (sender-pp-092.zoho.com. [135.84.80.237]) by mx.google.com with ESMTPS id o9si11834704oib.359.2017.07.17.02.04.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 17 Jul 2017 02:04:55 -0700 (PDT) Subject: Re: [PATCH v2] mm/vmalloc: terminate searching since one node found References: <596C7924.1010207@zoho.com> From: zijun_hu Message-ID: <596C7D99.5040208@zoho.com> Date: Mon, 17 Jul 2017 17:04:25 +0800 MIME-Version: 1.0 In-Reply-To: <596C7924.1010207@zoho.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Zhaoyang Huang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, zijun_hu@htc.com On 07/17/2017 04:45 PM, zijun_hu wrote: > On 07/17/2017 04:07 PM, Zhaoyang Huang wrote: >> It is no need to find the very beginning of the area within >> alloc_vmap_area, which can be done by judging each node during the process >> >> For current approach, the worst case is that the starting node which be found >> for searching the 'vmap_area_list' is close to the 'vstart', while the final >> available one is round to the tail(especially for the left branch). >> This commit have the list searching start at the first available node, which >> will save the time of walking the rb tree'(1)' and walking the list(2). >> >> vmap_area_root >> / \ >> tmp_next U >> / (1) >> tmp >> / >> ... >> / >> first(current approach) >> >> vmap_area_list->...->first->...->tmp->tmp_next > > the original code can ensure the following two points : > A, the result vamp_area has the lowest available address in the range [vstart, vend) > B, it can maintain the cached vamp_area node rightly which can speedup relative allocation > i suspect this patch maybe destroy the above two points >> (2) >> >> Signed-off-by: Zhaoyang Huang >> --- >> mm/vmalloc.c | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/mm/vmalloc.c b/mm/vmalloc.c >> index 34a1c3e..f833e07 100644 >> --- a/mm/vmalloc.c >> +++ b/mm/vmalloc.c >> @@ -459,9 +459,16 @@ static struct vmap_area *alloc_vmap_area(unsigned >> long size, >> >> while (n) { >> struct vmap_area *tmp; >> + struct vmap_area *tmp_next; >> tmp = rb_entry(n, struct vmap_area, rb_node); >> + tmp_next = list_next_entry(tmp, list); >> if (tmp->va_end >= addr) { >> first = tmp; >> + if (ALIGN(tmp->va_end, align) + size >> + < tmp_next->va_start) { >> + addr = ALIGN(tmp->va_end, align); >> + goto found; >> + } > is the aim vamp_area the lowest available one if the goto occurs ? > it will bypass the latter cached vamp_area info cached_hole_size update possibly if the goto occurs it think the aim area maybe don't locates the required range [vstart, vend) possibly. >> if (tmp->va_start <= addr) >> break; >> n = n->rb_left; >> -- >> 1.9.1 >> > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org