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 95B9AC433F5 for ; Thu, 7 Apr 2022 07:53:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242360AbiDGHzF (ORCPT ); Thu, 7 Apr 2022 03:55:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242332AbiDGHy4 (ORCPT ); Thu, 7 Apr 2022 03:54:56 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B737E1C4B23 for ; Thu, 7 Apr 2022 00:52:56 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4KYtrp6zp8z13VdT; Thu, 7 Apr 2022 15:52:26 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Thu, 7 Apr 2022 15:52:47 +0800 Received: from [10.174.178.55] (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Thu, 7 Apr 2022 15:52:54 +0800 Subject: Re: [PATCH RESEND v5 2/5] iova: Allow rcache range upper limit to be flexible To: John Garry , , , CC: , , , , , , , References: <1649071634-188535-1-git-send-email-john.garry@huawei.com> <1649071634-188535-3-git-send-email-john.garry@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <834447a0-675a-5978-8ffe-285ce09f4213@huawei.com> Date: Thu, 7 Apr 2022 15:52:53 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <1649071634-188535-3-git-send-email-john.garry@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/4/4 19:27, John Garry wrote: > Some low-level drivers may request DMA mappings whose IOVA length exceeds > that of the current rcache upper limit. > > This means that allocations for those IOVAs will never be cached, and > always must be allocated and freed from the RB tree per DMA mapping cycle. > This has a significant effect on performance, more so since commit > 4e89dce72521 ("iommu/iova: Retry from last rb tree node if iova search > fails"), as discussed at [0]. > > As a first step towards allowing the rcache range upper limit be > configured, hold this value in the IOVA rcache structure, and allocate > the rcaches separately. > > Delete macro IOVA_RANGE_CACHE_MAX_SIZE in case it's reused by mistake. > > [0] https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@huawei.com/ > > Signed-off-by: John Garry > --- > drivers/iommu/iova.c | 20 ++++++++++---------- > include/linux/iova.h | 3 +++ > 2 files changed, 13 insertions(+), 10 deletions(-) > > diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c > index db77aa675145..5c22b9187b79 100644 > --- a/drivers/iommu/iova.c > +++ b/drivers/iommu/iova.c > @@ -15,8 +15,6 @@ > /* The anchor node sits above the top of the usable address space */ > #define IOVA_ANCHOR ~0UL > > -#define IOVA_RANGE_CACHE_MAX_SIZE 6 /* log of max cached IOVA range size (in pages) */ > - > static bool iova_rcache_insert(struct iova_domain *iovad, > unsigned long pfn, > unsigned long size); > @@ -443,7 +441,7 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size, > * rounding up anything cacheable to make sure that can't happen. The > * order of the unadjusted size will still match upon freeing. > */ > - if (size < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1))) > + if (size < (1 << (iovad->rcache_max_size - 1))) > size = roundup_pow_of_two(size); > > iova_pfn = iova_rcache_get(iovad, size, limit_pfn + 1); > @@ -713,13 +711,15 @@ int iova_domain_init_rcaches(struct iova_domain *iovad) > unsigned int cpu; > int i, ret; > > - iovad->rcaches = kcalloc(IOVA_RANGE_CACHE_MAX_SIZE, > + iovad->rcache_max_size = 6; /* Arbitrarily high default */ It would be better to assign this constant value to iovad->rcache_max_size in init_iova_domain(). > + > + iovad->rcaches = kcalloc(iovad->rcache_max_size, > sizeof(struct iova_rcache), > GFP_KERNEL); > if (!iovad->rcaches) > return -ENOMEM; > > - for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) { > + for (i = 0; i < iovad->rcache_max_size; ++i) { > struct iova_cpu_rcache *cpu_rcache; > struct iova_rcache *rcache; > > @@ -816,7 +816,7 @@ static bool iova_rcache_insert(struct iova_domain *iovad, unsigned long pfn, > { > unsigned int log_size = order_base_2(size); > > - if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE) > + if (log_size >= iovad->rcache_max_size) > return false; > > return __iova_rcache_insert(iovad, &iovad->rcaches[log_size], pfn); > @@ -872,7 +872,7 @@ static unsigned long iova_rcache_get(struct iova_domain *iovad, > { > unsigned int log_size = order_base_2(size); > > - if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE || !iovad->rcaches) > + if (log_size >= iovad->rcache_max_size || !iovad->rcaches) > return 0; > > return __iova_rcache_get(&iovad->rcaches[log_size], limit_pfn - size); > @@ -888,7 +888,7 @@ static void free_iova_rcaches(struct iova_domain *iovad) > unsigned int cpu; > int i, j; > > - for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) { > + for (i = 0; i < iovad->rcache_max_size; ++i) { > rcache = &iovad->rcaches[i]; > if (!rcache->cpu_rcaches) > break; > @@ -916,7 +916,7 @@ static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad) > unsigned long flags; > int i; > > - for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) { > + for (i = 0; i < iovad->rcache_max_size; ++i) { > rcache = &iovad->rcaches[i]; > cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu); > spin_lock_irqsave(&cpu_rcache->lock, flags); > @@ -935,7 +935,7 @@ static void free_global_cached_iovas(struct iova_domain *iovad) > unsigned long flags; > int i, j; > > - for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) { > + for (i = 0; i < iovad->rcache_max_size; ++i) { > rcache = &iovad->rcaches[i]; > spin_lock_irqsave(&rcache->lock, flags); > for (j = 0; j < rcache->depot_size; ++j) { > diff --git a/include/linux/iova.h b/include/linux/iova.h > index 320a70e40233..02f7222fa85a 100644 > --- a/include/linux/iova.h > +++ b/include/linux/iova.h > @@ -38,6 +38,9 @@ struct iova_domain { > > struct iova_rcache *rcaches; > struct hlist_node cpuhp_dead; > + > + /* log of max cached IOVA range size (in pages) */ > + unsigned long rcache_max_size; > }; > > static inline unsigned long iova_size(struct iova *iova) > -- Regards, Zhen Lei