From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurence Oberman Subject: Re: [PATCH for v4.7] IB/srpt: Reduce QP buffer size Date: Thu, 23 Jun 2016 09:13:53 -0400 (EDT) Message-ID: <2016197898.863510.1466687633505.JavaMail.zimbra@redhat.com> References: <20160623073548.9883-1-bart.vanassche@sandisk.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160623073548.9883-1-bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Bart Van Assche Cc: Doug Ledford , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christoph Hellwig , Sagi Grimberg List-Id: linux-rdma@vger.kernel.org ----- Original Message ----- > From: "Bart Van Assche" > To: "Doug Ledford" > Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Laurence Oberman" , "Christoph Hellwig" , "Sagi > Grimberg" > Sent: Thursday, June 23, 2016 3:35:48 AM > Subject: [PATCH for v4.7] IB/srpt: Reduce QP buffer size > > The memory needed for the send and receive queues associated with > a QP is proportional to the max_sge parameter. The current value > of that parameter is such that with an mlx4 HCA the QP buffer size > is 8 MB. Since DMA is used for communication between HCA and CPU > that buffer either has to be allocated coherently or map_single() > must succeed for that buffer. Since large contiguous allocations > are fragile and since the maximum segment size for e.g. swiotlb > is 256 KB, reduce the max_sge parameter. This patch avoids that > the following text appears on the console after SRP logout and > relogin on a system equipped with multiple IB HCAs: > > mlx4_core 0000:05:00.0: swiotlb buffer is full (sz: 8388608 bytes) > swiotlb: coherent allocation failed for device 0000:05:00.0 size=8388608 > CPU: 11 PID: 148 Comm: kworker/11:1 Not tainted 4.7.0-rc4-dbg+ #1 > Call Trace: > [] dump_stack+0x67/0x92 > [] swiotlb_alloc_coherent+0x141/0x150 > [] x86_swiotlb_alloc_coherent+0x3e/0x50 > [] mlx4_buf_direct_alloc.isra.5+0x9a/0x120 [mlx4_core] > [] mlx4_buf_alloc+0x165/0x1a0 [mlx4_core] > [] create_qp_common.isra.29+0x57d/0xff0 [mlx4_ib] > [] mlx4_ib_create_qp+0x12a/0x3f0 [mlx4_ib] > [] ib_create_qp+0x3a/0x250 [ib_core] > [] srpt_cm_handler+0x4bb/0xcad [ib_srpt] > [] cm_process_work+0x20/0xf0 [ib_cm] > [] cm_work_handler+0x1ac0/0x2059 [ib_cm] > [] process_one_work+0x19d/0x490 > [] worker_thread+0x49/0x490 > [] kthread+0xea/0x100 > [] ret_from_fork+0x1f/0x40 > > Fixes: b99f8e4d7bcd ("IB/srpt: convert to the generic RDMA READ/WRITE API") > Signed-off-by: Bart Van Assche > Cc: Laurence Oberman > Cc: Christoph Hellwig > Cc: Sagi Grimberg > --- > drivers/infiniband/ulp/srpt/ib_srpt.c | 3 +-- > drivers/infiniband/ulp/srpt/ib_srpt.h | 1 + > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c > b/drivers/infiniband/ulp/srpt/ib_srpt.c > index e68b20cb..4a41556 100644 > --- a/drivers/infiniband/ulp/srpt/ib_srpt.c > +++ b/drivers/infiniband/ulp/srpt/ib_srpt.c > @@ -1638,8 +1638,7 @@ retry: > */ > qp_init->cap.max_send_wr = srp_sq_size / 2; > qp_init->cap.max_rdma_ctxs = srp_sq_size / 2; > - qp_init->cap.max_send_sge = max(sdev->device->attrs.max_sge_rd, > - sdev->device->attrs.max_sge); > + qp_init->cap.max_send_sge = SRPT_DEF_SG_PER_WQE; > qp_init->port_num = ch->sport->port; > > ch->qp = ib_create_qp(sdev->pd, qp_init); > diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.h > b/drivers/infiniband/ulp/srpt/ib_srpt.h > index fee6bfd..3890304 100644 > --- a/drivers/infiniband/ulp/srpt/ib_srpt.h > +++ b/drivers/infiniband/ulp/srpt/ib_srpt.h > @@ -106,6 +106,7 @@ enum { > SRP_LOGIN_RSP_MULTICHAN_MAINTAINED = 0x2, > > SRPT_DEF_SG_TABLESIZE = 128, > + SRPT_DEF_SG_PER_WQE = 16, > > MIN_SRPT_SQ_SIZE = 16, > DEF_SRPT_SQ_SIZE = 4096, > -- > 2.8.4 > > Thanks Bart I will test it today -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html