From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E81F1C282DD for ; Wed, 17 Apr 2019 21:58:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B392121850 for ; Wed, 17 Apr 2019 21:58:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555538311; bh=4XXD6tTFmQ1+9DwxhK4hDN6odEgdckanLva0b+h4AXU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=TZwsSRXIqyNxM252wmZ4sW3F0t94KyhrP5udOnbP470jdH1gW1OS2Pr0fbb/GxSRA iAA50yb6Tkoht2VEqQ9+0+2+ekw6K0JmFLWo6IwQzFRUuUYdsodfBL8CrAAuEBDSP2 GdICWmDX3qYJ+kwbtDtej/G+NDH6/XeK/jpl21Es= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387517AbfDQV6a (ORCPT ); Wed, 17 Apr 2019 17:58:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55036 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729782AbfDQV6a (ORCPT ); Wed, 17 Apr 2019 17:58:30 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id C52E2A95; Wed, 17 Apr 2019 21:58:28 +0000 (UTC) Date: Wed, 17 Apr 2019 14:58:27 -0700 From: Andrew Morton To: Roman Gushchin Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Matthew Wilcox , Johannes Weiner , Vlastimil Babka , Roman Gushchin Subject: Re: [PATCH v4 1/2] mm: refactor __vunmap() to avoid duplicated call to find_vm_area() Message-Id: <20190417145827.8b1c83bf22de8ba514f157e3@linux-foundation.org> In-Reply-To: <20190417194002.12369-2-guro@fb.com> References: <20190417194002.12369-1-guro@fb.com> <20190417194002.12369-2-guro@fb.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 17 Apr 2019 12:40:01 -0700 Roman Gushchin wrote: > __vunmap() calls find_vm_area() twice without an obvious reason: > first directly to get the area pointer, second indirectly by calling > remove_vm_area(), which is again searching for the area. > > To remove this redundancy, let's split remove_vm_area() into > __remove_vm_area(struct vmap_area *), which performs the actual area > removal, and remove_vm_area(const void *addr) wrapper, which can > be used everywhere, where it has been used before. > > On my test setup, I've got 5-10% speed up on vfree()'ing 1000000 > of 4-pages vmalloc blocks. > > Perf report before: > 22.64% cat [kernel.vmlinux] [k] free_pcppages_bulk > 10.30% cat [kernel.vmlinux] [k] __vunmap > 9.80% cat [kernel.vmlinux] [k] find_vmap_area > 8.11% cat [kernel.vmlinux] [k] vunmap_page_range > 4.20% cat [kernel.vmlinux] [k] __slab_free > 3.56% cat [kernel.vmlinux] [k] __list_del_entry_valid > 3.46% cat [kernel.vmlinux] [k] smp_call_function_many > 3.33% cat [kernel.vmlinux] [k] kfree > 3.32% cat [kernel.vmlinux] [k] free_unref_page > > Perf report after: > 23.01% cat [kernel.kallsyms] [k] free_pcppages_bulk > 9.46% cat [kernel.kallsyms] [k] __vunmap > 9.15% cat [kernel.kallsyms] [k] vunmap_page_range > 6.17% cat [kernel.kallsyms] [k] __slab_free > 5.61% cat [kernel.kallsyms] [k] kfree > 4.86% cat [kernel.kallsyms] [k] bad_range > 4.67% cat [kernel.kallsyms] [k] free_unref_page_commit > 4.24% cat [kernel.kallsyms] [k] __list_del_entry_valid > 3.68% cat [kernel.kallsyms] [k] free_unref_page > 3.65% cat [kernel.kallsyms] [k] __list_add_valid > 3.19% cat [kernel.kallsyms] [k] __purge_vmap_area_lazy > 3.10% cat [kernel.kallsyms] [k] find_vmap_area > 3.05% cat [kernel.kallsyms] [k] rcu_cblist_dequeue > > ... > > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2068,6 +2068,24 @@ struct vm_struct *find_vm_area(const void *addr) > return NULL; > } > > +static struct vm_struct *__remove_vm_area(struct vmap_area *va) > +{ > + struct vm_struct *vm = va->vm; > + > + might_sleep(); Where might __remove_vm_area() sleep? >From a quick scan I'm only seeing vfree(), and that has the might_sleep_if(!in_interrupt()). So perhaps we can remove this... > + spin_lock(&vmap_area_lock); > + va->vm = NULL; > + va->flags &= ~VM_VM_AREA; > + va->flags |= VM_LAZY_FREE; > + spin_unlock(&vmap_area_lock); > + > + kasan_free_shadow(vm); > + free_unmap_vmap_area(va); > + > + return vm; > +} > +