From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f197.google.com (mail-qk0-f197.google.com [209.85.220.197]) by kanga.kvack.org (Postfix) with ESMTP id D6F816B0008 for ; Thu, 1 Feb 2018 23:18:11 -0500 (EST) Received: by mail-qk0-f197.google.com with SMTP id u133so14861372qka.12 for ; Thu, 01 Feb 2018 20:18:11 -0800 (PST) Received: from aserp2130.oracle.com (aserp2130.oracle.com. [141.146.126.79]) by mx.google.com with ESMTPS id v8si1273873qkb.257.2018.02.01.20.18.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Feb 2018 20:18:11 -0800 (PST) Subject: Re: [RFC PATCH v1 00/13] lru_lock scalability References: <20180131230413.27653-1-daniel.m.jordan@oracle.com> <6bd1c8a5-c682-a3ce-1f9f-f1f53b4117a9@redhat.com> From: Daniel Jordan Message-ID: Date: Thu, 1 Feb 2018 23:18:01 -0500 MIME-Version: 1.0 In-Reply-To: <6bd1c8a5-c682-a3ce-1f9f-f1f53b4117a9@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Steven Whitehouse , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: aaron.lu@intel.com, ak@linux.intel.com, akpm@linux-foundation.org, Dave.Dice@oracle.com, dave@stgolabs.net, khandual@linux.vnet.ibm.com, ldufour@linux.vnet.ibm.com, mgorman@suse.de, mhocko@kernel.org, pasha.tatashin@oracle.com, steven.sistare@oracle.com, yossi.lev@oracle.com On 02/01/2018 10:54 AM, Steven Whitehouse wrote: > Hi, > > > On 31/01/18 23:04, daniel.m.jordan@oracle.com wrote: >> lru_lock, a per-node* spinlock that protects an LRU list, is one of the >> hottest locks in the kernel.A On some workloads on large machines, it >> shows up at the top of lock_stat. >> >> One way to improve lru_lock scalability is to introduce an array of locks, >> with each lock protecting certain batches of LRU pages. >> >> A A A A A A A A *ooooooooooo**ooooooooooo**ooooooooooo**oooo ... >> A A A A A A A A |A A A A A A A A A A ||A A A A A A A A A A ||A A A A A A A A A A || >> A A A A A A A A A \ batch 1 /A \ batch 2 /A \ batch 3 / >> >> In this ASCII depiction of an LRU, a page is represented with either '*' >> or 'o'.A An asterisk indicates a sentinel page, which is a page at the >> edge of a batch.A An 'o' indicates a non-sentinel page. >> >> To remove a non-sentinel LRU page, only one lock from the array is >> required.A This allows multiple threads to remove pages from different >> batches simultaneously.A A sentinel page requires lru_lock in addition to >> a lock from the array. >> >> Full performance numbers appear in the last patch in this series, but this >> prototype allows a microbenchmark to do up to 28% more page faults per >> second with 16 or more concurrent processes. >> >> This work was developed in collaboration with Steve Sistare. >> >> Note: This is an early prototype.A I'm submitting it now to support my >> request to attend LSF/MM, as well as get early feedback on the idea.A Any >> comments appreciated. >> >> >> * lru_lock is actually per-memcg, but without memcg's in the picture it >> A A becomes per-node. > GFS2 has an lru list for glocks, which can be contended under certain workloads. Work is still ongoing to figure out exactly why, but this looks like it might be a good approach to that issue too. The main purpose of GFS2's lru list is to allow shrinking of the glocks under memory pressure via the gfs2_scan_glock_lru() function, and it looks like this type of approach could be used there to improve the scalability, Glad to hear that this could help in gfs2 as well. Hopefully struct gfs2_glock is less space constrained than struct page for storing the few bits of metadata that this approach requires. Daniel > > Steve. > >> >> Aaron Lu (1): >> A A mm: add a percpu_pagelist_batch sysctl interface >> >> Daniel Jordan (12): >> A A mm: allow compaction to be disabled >> A A mm: add lock array to pgdat and batch fields to struct page >> A A mm: introduce struct lru_list_head in lruvec to hold per-LRU batch >> A A A A info >> A A mm: add batching logic to add/delete/move API's >> A A mm: add lru_[un]lock_all APIs >> A A mm: convert to-be-refactored lru_lock callsites to lock-all API >> A A mm: temporarily convert lru_lock callsites to lock-all API >> A A mm: introduce add-only version of pagevec_lru_move_fn >> A A mm: add LRU batch lock API's >> A A mm: use lru_batch locking in release_pages >> A A mm: split up release_pages into non-sentinel and sentinel passes >> A A mm: splice local lists onto the front of the LRU >> >> A include/linux/mm_inline.h | 209 +++++++++++++++++++++++++++++++++++++++++++++- >> A include/linux/mm_types.hA |A A 5 ++ >> A include/linux/mmzone.hA A A |A 25 +++++- >> A kernel/sysctl.cA A A A A A A A A A |A A 9 ++ >> A mm/KconfigA A A A A A A A A A A A A A A |A A 1 - >> A mm/huge_memory.cA A A A A A A A A |A A 6 +- >> A mm/memcontrol.cA A A A A A A A A A |A A 5 +- >> A mm/mlock.cA A A A A A A A A A A A A A A |A 11 +-- >> A mm/mmzone.cA A A A A A A A A A A A A A |A A 7 +- >> A mm/page_alloc.cA A A A A A A A A A |A 43 +++++++++- >> A mm/page_idle.cA A A A A A A A A A A |A A 4 +- >> A mm/swap.cA A A A A A A A A A A A A A A A | 208 ++++++++++++++++++++++++++++++++++++--------- >> A mm/vmscan.cA A A A A A A A A A A A A A |A 49 +++++------ >> A 13 files changed, 500 insertions(+), 82 deletions(-) >> > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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