From mboxrd@z Thu Jan 1 00:00:00 1970 From: Qing Huang Subject: Re: [PATCH v3] mlx4_core: allocate ICM memory in page size chunks Date: Thu, 17 May 2018 14:45:20 -0700 Message-ID: <19b7818e-16f6-2349-dc34-245c2f215f6f@oracle.com> References: <20180517205343.8401-1-qing.huang@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, gi-oh.kim@profitbricks.com To: Eric Dumazet , tariqt@mellanox.com, davem@davemloft.net, haakon.bugge@oracle.com, yanjun.zhu@oracle.com Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 5/17/2018 2:14 PM, Eric Dumazet wrote: > On 05/17/2018 01:53 PM, Qing Huang wrote: >> When a system is under memory presure (high usage with fragments), >> the original 256KB ICM chunk allocations will likely trigger kernel >> memory management to enter slow path doing memory compact/migration >> ops in order to complete high order memory allocations. >> >> When that happens, user processes calling uverb APIs may get stuck >> for more than 120s easily even though there are a lot of free pages >> in smaller chunks available in the system. >> >> Syslog: >> ... >> Dec 10 09:04:51 slcc03db02 kernel: [397078.572732] INFO: task >> oracle_205573_e:205573 blocked for more than 120 seconds. >> ... >> > NACK on this patch. > > You have been asked repeatedly to use kvmalloc() > > This is not a minor suggestion. > > Take a look athttps://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d8c13f2271ec5178c52fbde072ec7b562651ed9d Would you please take a look at how table->icm is being used in the mlx4 driver? It's a meta data used for individual pointer variable referencing, not as data frag or in/out buffer. It has no need for contiguous phy. memory. Thanks. > And you'll understand some people care about this. > > Strongly. > > Thanks. >