From: vjitta@codeaurora.org To: joro@8bytes.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Cc: vinmenon@codeaurora.org, kernel-team@android.com, vjitta@codeaurora.org Subject: [PATCH] iommu/iova: Retry from last rb tree node if iova search fails Date: Thu, 7 May 2020 01:31:57 +0530 [thread overview] Message-ID: <1588795317-20879-1-git-send-email-vjitta@codeaurora.org> (raw) From: Vijayanand Jitta <vjitta@codeaurora.org> When ever a new iova alloc request comes iova is always searched from the cached node and the nodes which are previous to cached node. So, even if there is free iova space available in the nodes which are next to the cached node iova allocation can still fail because of this approach. Consider the following sequence of iova alloc and frees on 1GB of iova space 1) alloc - 500MB 2) alloc - 12MB 3) alloc - 499MB 4) free - 12MB which was allocated in step 2 5) alloc - 13MB After the above sequence we will have 12MB of free iova space and cached node will be pointing to the iova pfn of last alloc of 13MB which will be the lowest iova pfn of that iova space. Now if we get an alloc request of 2MB we just search from cached node and then look for lower iova pfn's for free iova and as they aren't any, iova alloc fails though there is 12MB of free iova space. To avoid such iova search failures do a retry from the last rb tree node when iova search fails, this will search the entire tree and get an iova if its available Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org> --- drivers/iommu/iova.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 0e6a953..2985222 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -186,6 +186,7 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, unsigned long flags; unsigned long new_pfn; unsigned long align_mask = ~0UL; + bool retry = false; if (size_aligned) align_mask <<= fls_long(size - 1); @@ -198,6 +199,8 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, curr = __get_cached_rbnode(iovad, limit_pfn); curr_iova = rb_entry(curr, struct iova, node); + +retry_search: do { limit_pfn = min(limit_pfn, curr_iova->pfn_lo); new_pfn = (limit_pfn - size) & align_mask; @@ -207,6 +210,14 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, } while (curr && new_pfn <= curr_iova->pfn_hi); if (limit_pfn < size || new_pfn < iovad->start_pfn) { + if (!retry) { + curr = rb_last(&iovad->rbroot); + curr_iova = rb_entry(curr, struct iova, node); + limit_pfn = curr_iova->pfn_lo; + retry = true; + goto retry_search; + } + iovad->max32_alloc_size = size; goto iova32_full; } -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation 1.9.1
WARNING: multiple messages have this Message-ID (diff)
From: vjitta@codeaurora.org To: joro@8bytes.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Cc: vjitta@codeaurora.org, vinmenon@codeaurora.org, kernel-team@android.com Subject: [PATCH] iommu/iova: Retry from last rb tree node if iova search fails Date: Thu, 7 May 2020 01:31:57 +0530 [thread overview] Message-ID: <1588795317-20879-1-git-send-email-vjitta@codeaurora.org> (raw) From: Vijayanand Jitta <vjitta@codeaurora.org> When ever a new iova alloc request comes iova is always searched from the cached node and the nodes which are previous to cached node. So, even if there is free iova space available in the nodes which are next to the cached node iova allocation can still fail because of this approach. Consider the following sequence of iova alloc and frees on 1GB of iova space 1) alloc - 500MB 2) alloc - 12MB 3) alloc - 499MB 4) free - 12MB which was allocated in step 2 5) alloc - 13MB After the above sequence we will have 12MB of free iova space and cached node will be pointing to the iova pfn of last alloc of 13MB which will be the lowest iova pfn of that iova space. Now if we get an alloc request of 2MB we just search from cached node and then look for lower iova pfn's for free iova and as they aren't any, iova alloc fails though there is 12MB of free iova space. To avoid such iova search failures do a retry from the last rb tree node when iova search fails, this will search the entire tree and get an iova if its available Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org> --- drivers/iommu/iova.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 0e6a953..2985222 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -186,6 +186,7 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, unsigned long flags; unsigned long new_pfn; unsigned long align_mask = ~0UL; + bool retry = false; if (size_aligned) align_mask <<= fls_long(size - 1); @@ -198,6 +199,8 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, curr = __get_cached_rbnode(iovad, limit_pfn); curr_iova = rb_entry(curr, struct iova, node); + +retry_search: do { limit_pfn = min(limit_pfn, curr_iova->pfn_lo); new_pfn = (limit_pfn - size) & align_mask; @@ -207,6 +210,14 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, } while (curr && new_pfn <= curr_iova->pfn_hi); if (limit_pfn < size || new_pfn < iovad->start_pfn) { + if (!retry) { + curr = rb_last(&iovad->rbroot); + curr_iova = rb_entry(curr, struct iova, node); + limit_pfn = curr_iova->pfn_lo; + retry = true; + goto retry_search; + } + iovad->max32_alloc_size = size; goto iova32_full; } -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation 1.9.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next reply other threads:[~2020-05-06 20:03 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-05-06 20:01 vjitta [this message] 2020-05-06 20:01 ` [PATCH] iommu/iova: Retry from last rb tree node if iova search fails vjitta 2020-05-07 13:24 ` Robin Murphy 2020-05-07 13:24 ` Robin Murphy 2020-05-07 18:22 ` Ajay kumar 2020-05-07 18:22 ` Ajay kumar 2020-05-07 18:33 ` Robin Murphy 2020-05-07 18:33 ` Robin Murphy 2020-05-08 18:55 ` Vijayanand Jitta 2020-05-08 18:55 ` Vijayanand Jitta 2020-05-11 11:14 ` Vijayanand Jitta 2020-05-11 11:14 ` Vijayanand Jitta
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=1588795317-20879-1-git-send-email-vjitta@codeaurora.org \ --to=vjitta@codeaurora.org \ --cc=iommu@lists.linux-foundation.org \ --cc=joro@8bytes.org \ --cc=kernel-team@android.com \ --cc=linux-kernel@vger.kernel.org \ --cc=vinmenon@codeaurora.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.