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GET /api/patches/27815/?format=api
{ "id": 27815, "url": "https://patches.dpdk.org/api/patches/27815/?format=api", "web_url": "https://patches.dpdk.org/project/dpdk/patch/1503499644-29432-4-git-send-email-erik.g.carrillo@intel.com/", "project": { "id": 1, "url": "https://patches.dpdk.org/api/projects/1/?format=api", "name": "DPDK", "link_name": "dpdk", "list_id": "dev.dpdk.org", "list_email": "dev@dpdk.org", "web_url": "http://core.dpdk.org", "scm_url": "git://dpdk.org/dpdk", "webscm_url": "http://git.dpdk.org/dpdk", "list_archive_url": "https://inbox.dpdk.org/dev", "list_archive_url_format": "https://inbox.dpdk.org/dev/{}", "commit_url_format": "" }, "msgid": "<1503499644-29432-4-git-send-email-erik.g.carrillo@intel.com>", "list_archive_url": "https://inbox.dpdk.org/dev/1503499644-29432-4-git-send-email-erik.g.carrillo@intel.com", "date": "2017-08-23T14:47:24", "name": "[dpdk-dev,3/3] doc: update timer lib docs", "commit_ref": null, "pull_url": null, "state": "superseded", "archived": true, "hash": "6066279da1c5a1d72f01304e62b2b40bbb2bcb56", "submitter": { "id": 762, "url": "https://patches.dpdk.org/api/people/762/?format=api", "name": "Carrillo, Erik G", "email": "erik.g.carrillo@intel.com" }, "delegate": null, "mbox": "https://patches.dpdk.org/project/dpdk/patch/1503499644-29432-4-git-send-email-erik.g.carrillo@intel.com/mbox/", "series": [], "comments": "https://patches.dpdk.org/api/patches/27815/comments/", "check": "success", "checks": "https://patches.dpdk.org/api/patches/27815/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<dev-bounces@dpdk.org>", "X-Original-To": "patchwork@dpdk.org", "Delivered-To": "patchwork@dpdk.org", "Received": [ "from [92.243.14.124] (localhost [IPv6:::1])\n\tby dpdk.org (Postfix) with ESMTP id AD08C7D62;\n\tWed, 23 Aug 2017 16:48:08 +0200 (CEST)", "from mga06.intel.com (mga06.intel.com [134.134.136.31])\n\tby dpdk.org (Postfix) with ESMTP id 56BBC7D36\n\tfor <dev@dpdk.org>; Wed, 23 Aug 2017 16:48:06 +0200 (CEST)", "from orsmga002.jf.intel.com ([10.7.209.21])\n\tby orsmga104.jf.intel.com with ESMTP; 23 Aug 2017 07:48:05 -0700", "from txasoft-yocto.an.intel.com (HELO txasoft-yocto.an.intel.com.)\n\t([10.123.72.111])\n\tby orsmga002.jf.intel.com with ESMTP; 23 Aug 2017 07:48:03 -0700" ], "X-ExtLoop1": "1", "X-IronPort-AV": "E=Sophos;i=\"5.41,417,1498546800\"; d=\"scan'208\";a=\"127405187\"", "From": "Gabriel Carrillo <erik.g.carrillo@intel.com>", "To": "rsanford@akamai.com", "Cc": "dev@dpdk.org", "Date": "Wed, 23 Aug 2017 09:47:24 -0500", "Message-Id": "<1503499644-29432-4-git-send-email-erik.g.carrillo@intel.com>", "X-Mailer": "git-send-email 1.7.10", "In-Reply-To": "<1503499644-29432-1-git-send-email-erik.g.carrillo@intel.com>", "References": "<1503499644-29432-1-git-send-email-erik.g.carrillo@intel.com>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=UTF-8", "Content-Transfer-Encoding": "8bit", "Subject": "[dpdk-dev] =?utf-8?q?=5BPATCH_3/3=5D_doc=3A_update_timer_lib_docs?=", "X-BeenThere": "dev@dpdk.org", "X-Mailman-Version": "2.1.15", "Precedence": "list", "List-Id": "DPDK patches and discussions <dev.dpdk.org>", "List-Unsubscribe": "<http://dpdk.org/ml/options/dev>,\n\t<mailto:dev-request@dpdk.org?subject=unsubscribe>", "List-Archive": "<http://dpdk.org/ml/archives/dev/>", "List-Post": "<mailto:dev@dpdk.org>", "List-Help": "<mailto:dev-request@dpdk.org?subject=help>", "List-Subscribe": "<http://dpdk.org/ml/listinfo/dev>,\n\t<mailto:dev-request@dpdk.org?subject=subscribe>", "Errors-To": "dev-bounces@dpdk.org", "Sender": "\"dev\" <dev-bounces@dpdk.org>" }, "content": "This change updates the timer library documentation to\nreflect a change to the organization of the skiplists\nin the implementation.\n\nSigned-off-by: Gabriel Carrillo <erik.g.carrillo@intel.com>\n---\n doc/guides/prog_guide/timer_lib.rst | 19 ++++++++++---------\n 1 file changed, 10 insertions(+), 9 deletions(-)", "diff": "diff --git a/doc/guides/prog_guide/timer_lib.rst b/doc/guides/prog_guide/timer_lib.rst\nindex f437417..f94ffaa 100644\n--- a/doc/guides/prog_guide/timer_lib.rst\n+++ b/doc/guides/prog_guide/timer_lib.rst\n@@ -1,5 +1,5 @@\n .. BSD LICENSE\n- Copyright(c) 2010-2014 Intel Corporation. All rights reserved.\n+ Copyright(c) 2010-2017 Intel Corporation. All rights reserved.\n All rights reserved.\n \n Redistribution and use in source and binary forms, with or without\n@@ -53,16 +53,17 @@ Refer to the `callout manual <http://www.daemon-systems.org/man/callout.9.html>`\n Implementation Details\n ----------------------\n \n-Timers are tracked on a per-lcore basis,\n-with all pending timers for a core being maintained in order of timer expiry in a skiplist data structure.\n-The skiplist used has ten levels and each entry in the table appears in each level with probability ¼^level.\n+Timers are tracked in a per-lcore array of skiplist data structures; each\n+lcore has one skiplist corresponding to each other lcore that could load a timer on it. All pending\n+timers in each skiplist are maintained in order of timer expiry.\n+Each skiplist has ten levels and each entry in the table appears in each level with probability ¼^level.\n This means that all entries are present in level 0, 1 in every 4 entries is present at level 1,\n one in every 16 at level 2 and so on up to level 9.\n This means that adding and removing entries from the timer list for a core can be done in log(n) time,\n up to 4^10 entries, that is, approximately 1,000,000 timers per lcore.\n \n A timer structure contains a special field called status,\n-which is a union of a timer state (stopped, pending, running, config) and an owner (lcore id).\n+which is a union of a timer state (stopped, pending, running, config), an installer (lcore id), and an owner (lcore id).\n Depending on the timer state, we know if a timer is present in a list or not:\n \n * STOPPED: no owner, not in a list\n@@ -77,17 +78,17 @@ Resetting or stopping a timer while it is in a CONFIG or RUNNING state is not al\n When modifying the state of a timer,\n a Compare And Swap instruction should be used to guarantee that the status (state+owner) is modified atomically.\n \n-Inside the rte_timer_manage() function,\n-the skiplist is used as a regular list by iterating along the level 0 list, which contains all timer entries,\n+Inside the rte_timer_manage() function, each of an lcore's skiplists is traversed in sequence.\n+Each skiplist is used as a regular list by iterating along the level 0 list, which contains all timer entries,\n until an entry which has not yet expired has been encountered.\n-To improve performance in the case where there are entries in the timer list but none of those timers have yet expired,\n+To improve performance in the case where there are entries in a skiplist but none of those timers have yet expired,\n the expiry time of the first list entry is maintained within the per-core timer list structure itself.\n On 64-bit platforms, this value can be checked without the need to take a lock on the overall structure.\n (Since expiry times are maintained as 64-bit values,\n a check on the value cannot be done on 32-bit platforms without using either a compare-and-swap (CAS) instruction or using a lock,\n so this additional check is skipped in favor of checking as normal once the lock has been taken.)\n On both 64-bit and 32-bit platforms,\n-a call to rte_timer_manage() returns without taking a lock in the case where the timer list for the calling core is empty.\n+rte_timer_manage() can continue on to an lcore's next skiplist without taking a lock in the case where a timer list is empty.\n \n Use Cases\n ---------\n", "prefixes": [ "dpdk-dev", "3/3" ] }