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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0429C4332F for ; Thu, 22 Dec 2022 20:06:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229545AbiLVUGT (ORCPT ); Thu, 22 Dec 2022 15:06:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229504AbiLVUGP (ORCPT ); Thu, 22 Dec 2022 15:06:15 -0500 Received: from mail-wr1-x429.google.com (mail-wr1-x429.google.com [IPv6:2a00:1450:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69B381A816 for ; Thu, 22 Dec 2022 12:06:14 -0800 (PST) Received: by mail-wr1-x429.google.com with SMTP id i7so2719658wrv.8 for ; Thu, 22 Dec 2022 12:06:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=RZJWly5kBebpQU0okqF7TXgSEM1mQ0IrTkUDNeGNEww=; b=M7mgkYdGCUsFmj3AdjvMMkSpff/r8gGvOLnk6G6r28Hmm6hkUoVbsIj5aUScUp32OQ Fs4mGUJMO+kVN3fyvnCDNVb3LxeaapmQp1bfm2vq+6LAHIqDSZ0SGE9URDE5tkenwTjK UlkK6pMuQZ7yVKf34aqBuNzne12EUN8pryeYtD50paVRIBI8wL2lxAWtkKAIOYtaXczF IwpsmCWY0SyErNUpIL8MWCwAdKwfc3ghCMeV4P9jfwNmkn9nqH94p/yTwu2zpQ5XOWN8 HjlDNt5K1nov6SHUI425oTpjFNhwcum/630m8uZ6BvpJadRAAqbv7Pa2erDJe5UhEEg4 MuGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=RZJWly5kBebpQU0okqF7TXgSEM1mQ0IrTkUDNeGNEww=; b=1l4s0zakW1Z38lKAzWmwQwYGEHln5Nm0M2CYBsho8PRganpvCkIeWCLakwfroZVV1i 6s6hSEw98N1N5EWqlzV4IlVLE+CK1/cFH2+Lss60ixAPPsr52ZhAc53+e5oAPg8gXtzI rOcosAZ4ILjL2dVIXG8f3n8MLjXvnh9eRNqEKG4J/ycl5FCPyNerwf4GsaJy58w2CW++ of8JDLgDP7Fl8i/3ojH7yraccQyxy1zfeQP0WZ2qGDCPmEK4oGi48eusWimrDbvK3zwl TKQPXXRuBnaZiHdokqxauYJHiB7Vh8LMCVQf/k8E9JwM88HkiYuowd3S51HO8H1rEXMW pvOQ== X-Gm-Message-State: AFqh2kqAEykvrqFrQAUnCitfDJr6aK7mmoDszhBwVCaj+X77yOQl7lNc hoGlicsvdDDVT4+EGZQiho0= X-Google-Smtp-Source: AMrXdXve9X9xpjXpQvMkY7Gu8MBnYGGuP6vof+BTZ571QEMPAzD+ZO5QPAtN3FbO8KvlM4Sa/WF3Zg== X-Received: by 2002:a05:6000:49:b0:242:6777:c7e2 with SMTP id k9-20020a056000004900b002426777c7e2mr3736136wrx.31.1671739572912; Thu, 22 Dec 2022 12:06:12 -0800 (PST) Received: from localhost ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.gmail.com with ESMTPSA id o2-20020a5d58c2000000b0026a4bb75477sm1348793wrf.28.2022.12.22.12.06.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Dec 2022 12:06:12 -0800 (PST) Date: Thu, 22 Dec 2022 20:06:11 +0000 From: Lorenzo Stoakes To: "Uladzislau Rezki (Sony)" Cc: Andrew Morton , linux-mm@kvack.org, LKML , Baoquan He , Christoph Hellwig , Matthew Wilcox , Nicholas Piggin , Oleksiy Avramchenko , Roman Gushchin Subject: Re: [PATCH v3 1/3] mm: vmalloc: Avoid calling __find_vmap_area() twice in __vunmap() Message-ID: References: <20221222190022.134380-1-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221222190022.134380-1-urezki@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org n Thu, Dec 22, 2022 at 08:00:20PM +0100, Uladzislau Rezki (Sony) wrote: > Currently the __vunmap() path calls __find_vmap_area() twice. Once on > entry to check that the area exists, then inside the remove_vm_area() > function which also performs a new search for the VA. > > In order to improvie it from a performance point of view we split > remove_vm_area() into two new parts: > - find_unlink_vmap_area() that does a search and unlink from tree; > - __remove_vm_area() that removes without searching. > > In this case there is no any functional change for remove_vm_area() > whereas vm_remove_mappings(), where a second search happens, switches > to the __remove_vm_area() variant where the already detached VA is > passed as a parameter, so there is no need to find it again. > > Performance wise, i use test_vmalloc.sh with 32 threads doing alloc > free on a 64-CPUs-x86_64-box: > > perf without this patch: > - 31.41% 0.50% vmalloc_test/10 [kernel.vmlinux] [k] __vunmap > - 30.92% __vunmap > - 17.67% _raw_spin_lock > native_queued_spin_lock_slowpath > - 12.33% remove_vm_area > - 11.79% free_vmap_area_noflush > - 11.18% _raw_spin_lock > native_queued_spin_lock_slowpath > 0.76% free_unref_page > > perf with this patch: > - 11.35% 0.13% vmalloc_test/14 [kernel.vmlinux] [k] __vunmap > - 11.23% __vunmap > - 8.28% find_unlink_vmap_area > - 7.95% _raw_spin_lock > 7.44% native_queued_spin_lock_slowpath > - 1.93% free_vmap_area_noflush > - 0.56% _raw_spin_lock > 0.53% native_queued_spin_lock_slowpath > 0.60% __vunmap_range_noflush > > __vunmap() consumes around ~20% less CPU cycles on this test. > > v2 -> v3: > - update commit message; > - rename the vm_remove_mappings() to the va_remove_mappings(); > - move va-unlinking to the callers so the free_vmap_area_noflush() > now expects a VA that has been disconnected; > - eliminate a local variable in the remove_vm_area(). > > Reported-by: Roman Gushchin > Signed-off-by: Uladzislau Rezki (Sony) > --- > mm/vmalloc.c | 77 ++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 47 insertions(+), 30 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 9e30f0b39203..eb91ecaa7277 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1815,9 +1815,9 @@ static void drain_vmap_area_work(struct work_struct *work) > } > > /* > - * Free a vmap area, caller ensuring that the area has been unmapped > - * and flush_cache_vunmap had been called for the correct range > - * previously. > + * Free a vmap area, caller ensuring that the area has been unmapped, > + * unlinked and flush_cache_vunmap had been called for the correct > + * range previously. > */ > static void free_vmap_area_noflush(struct vmap_area *va) > { > @@ -1825,9 +1825,8 @@ static void free_vmap_area_noflush(struct vmap_area *va) > unsigned long va_start = va->va_start; > unsigned long nr_lazy; > > - spin_lock(&vmap_area_lock); > - unlink_va(va, &vmap_area_root); > - spin_unlock(&vmap_area_lock); > + if (WARN_ON_ONCE(!list_empty(&va->list))) > + return; > > nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> > PAGE_SHIFT, &vmap_lazy_nr); > @@ -1871,6 +1870,19 @@ struct vmap_area *find_vmap_area(unsigned long addr) > return va; > } > > +static struct vmap_area *find_unlink_vmap_area(unsigned long addr) > +{ > + struct vmap_area *va; > + > + spin_lock(&vmap_area_lock); > + va = __find_vmap_area(addr, &vmap_area_root); > + if (va) > + unlink_va(va, &vmap_area_root); > + spin_unlock(&vmap_area_lock); > + > + return va; > +} > + > /*** Per cpu kva allocator ***/ > > /* > @@ -2015,6 +2027,10 @@ static void free_vmap_block(struct vmap_block *vb) > tmp = xa_erase(&vmap_blocks, addr_to_vb_idx(vb->va->va_start)); > BUG_ON(tmp != vb); > > + spin_lock(&vmap_area_lock); > + unlink_va(vb->va, &vmap_area_root); > + spin_unlock(&vmap_area_lock); > + > free_vmap_area_noflush(vb->va); > kfree_rcu(vb, rcu_head); > } > @@ -2591,6 +2607,20 @@ struct vm_struct *find_vm_area(const void *addr) > return va->vm; > } > > +static struct vm_struct *__remove_vm_area(struct vmap_area *va) > +{ > + struct vm_struct *vm; > + > + if (!va || !va->vm) > + return NULL; > + > + vm = va->vm; > + kasan_free_module_shadow(vm); > + free_unmap_vmap_area(va); > + > + return vm; > +} > + > /** > * remove_vm_area - find and remove a continuous kernel virtual area > * @addr: base address > @@ -2603,26 +2633,10 @@ struct vm_struct *find_vm_area(const void *addr) > */ > struct vm_struct *remove_vm_area(const void *addr) > { > - struct vmap_area *va; > - > might_sleep(); > > - spin_lock(&vmap_area_lock); > - va = __find_vmap_area((unsigned long)addr, &vmap_area_root); > - if (va && va->vm) { > - struct vm_struct *vm = va->vm; > - > - va->vm = NULL; > - spin_unlock(&vmap_area_lock); > - > - kasan_free_module_shadow(vm); > - free_unmap_vmap_area(va); > - > - return vm; > - } > - > - spin_unlock(&vmap_area_lock); > - return NULL; > + return __remove_vm_area( > + find_unlink_vmap_area((unsigned long) addr)); > } > > static inline void set_area_direct_map(const struct vm_struct *area, > @@ -2636,16 +2650,17 @@ static inline void set_area_direct_map(const struct vm_struct *area, > set_direct_map(area->pages[i]); > } > > -/* Handle removing and resetting vm mappings related to the vm_struct. */ > -static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) > +/* Handle removing and resetting vm mappings related to the VA's vm_struct. */ > +static void va_remove_mappings(struct vmap_area *va, int deallocate_pages) > { > + struct vm_struct *area = va->vm; > unsigned long start = ULONG_MAX, end = 0; > unsigned int page_order = vm_area_page_order(area); > int flush_reset = area->flags & VM_FLUSH_RESET_PERMS; > int flush_dmap = 0; > int i; > > - remove_vm_area(area->addr); > + __remove_vm_area(va); > > /* If this is not VM_FLUSH_RESET_PERMS memory, no need for the below. */ > if (!flush_reset) > @@ -2690,6 +2705,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) > static void __vunmap(const void *addr, int deallocate_pages) > { > struct vm_struct *area; > + struct vmap_area *va; > > if (!addr) > return; > @@ -2698,19 +2714,20 @@ static void __vunmap(const void *addr, int deallocate_pages) > addr)) > return; > > - area = find_vm_area(addr); > - if (unlikely(!area)) { > + va = find_unlink_vmap_area((unsigned long)addr); > + if (unlikely(!va)) { > WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n", > addr); > return; > } > > + area = va->vm; > debug_check_no_locks_freed(area->addr, get_vm_area_size(area)); > debug_check_no_obj_freed(area->addr, get_vm_area_size(area)); > > kasan_poison_vmalloc(area->addr, get_vm_area_size(area)); > > - vm_remove_mappings(area, deallocate_pages); > + va_remove_mappings(va, deallocate_pages); > > if (deallocate_pages) { > int i; > -- > 2.30.2 > All looks good to me! Great work! Feel free to add the below to all patches in series:- Reviewed-by: Lorenzo Stoakes