On Wed, Apr 01, 2015 at 01:17:19PM -0400, ira.weiny wrote: > On Mon, Mar 23, 2015 at 11:17:49AM -0600, Jason Gunthorpe wrote: > > On Sun, Mar 22, 2015 at 11:21:50AM +0200, Yuval Shaia wrote: > > > On Sun, Mar 15, 2015 at 05:16:16PM +0200, Yuval Shaia wrote: > > > > Hi, > > > > I didn't got any further comments on this one. > > > > Any idea why SG in CM is un-welcome? > > > By mistake I sent a private mail only. > > > Cc: Roland Dreier <roland@xxxxxxxxxx> > > > Cc: Sean Hefty <sean.hefty@xxxxxxxxx> > > > Cc: Hal Rosenstock <hal.rosenstock@xxxxxxxxx> > > > > > > Your advice would be very appreciated. > > > > I haven't looked in detail at the patch, but in principle, using S/G > > when ever possible should be the default, even if this creates a > > performance regression. > > > > It is well known that high order allocations are problematic in Linux > > and should be avoided, and I also have seen systems blow up because of > > high order IPoIB allocations. > > > > That said, there may be cases where S/G is not possible, you should > > try and get Mellanox to comment if all their offloads work on all > > their cards when S/G is used. Work may be required to resolve any of > > these constraints. I'd like to belive there is some reason why we've > > been doing high order allocations for so many years. > > > > FWIW, I would probably choose to default S/G over any other offload > > acceleration. > > I concur with Jason's assessment. > > As Yann asked before: > > What hardware have you tested this on? Do you have any performance > measurements? Or do you have a reproducer for some of the allocation issues > which have been seen? Tested on Mellanox MT26428. Have here also CX3, will update if there will be an issue. No impact on performances. I did not try to reproduce the issue but people that do got this dump: pr 7 09:33:30 dbnode kernel: Call Trace: Apr 7 09:33:30 dbnode kernel: [<ffffffff810ddf74>] __alloc_pages_nodemask+0x524/0x595 Apr 7 09:33:30 dbnode kernel: [<ffffffff8110da3f>] kmem_getpages+0x4f/0xf4 Apr 7 09:33:30 dbnode kernel: [<ffffffff8110dc12>] fallback_alloc+0x12e/0x1ce Apr 7 09:33:30 dbnode kernel: [<ffffffff8110ddd3>] ____cache_alloc_node+0x121/0x134 Apr 7 09:33:30 dbnode kernel: [<ffffffff8110e3f3>] kmem_cache_alloc_node_notrace+0x84/0xb9 Apr 7 09:33:30 dbnode kernel: [<ffffffff8110e46e>] __kmalloc_node+0x46/0x73 Apr 7 09:33:30 dbnode kernel: [<ffffffff813b9aa8>] ? __alloc_skb+0x72/0x13d Apr 7 09:33:30 dbnode kernel: [<ffffffff813b9aa8>] __alloc_skb+0x72/0x13d Apr 7 09:33:30 dbnode kernel: [<ffffffff813f2364>] sk_stream_alloc_skb+0x3d/0xaf Apr 7 09:33:30 dbnode kernel: [<ffffffff813f35b5>] tcp_sendmsg+0x176/0x6cf Apr 7 09:33:30 dbnode kernel: [<ffffffff813b0d5f>] __sock_sendmsg+0x5e/0x67 Apr 7 09:33:30 dbnode kernel: [<ffffffff813b1644>] sock_sendmsg+0xcc/0xe5 Apr 7 09:33:30 dbnode kernel: [<ffffffff810b4d09>] ? delayacct_end+0x7d/0x88 Apr 7 09:33:30 dbnode kernel: [<ffffffff8104a3b0>] ? delayacct_blkio_end+0x26/0x40 Apr 7 09:33:30 dbnode kernel: [<ffffffff81077030>] ? autoremove_wake_function+0x0/0x3d Apr 7 09:33:30 dbnode kernel: [<ffffffff81456f1d>] ? __wait_on_bit+0x6c/0x7c Apr 7 09:33:30 dbnode kernel: [<ffffffff810d7b70>] ? sync_page+0x0/0x4d Apr 7 09:33:30 dbnode kernel: [<ffffffff8111656e>] ? __pfn_to_section+0x12/0x14 Apr 7 09:33:30 dbnode kernel: [<ffffffff811165a2>] ? lookup_page_cgroup+0x32/0x48 Apr 7 09:33:30 dbnode kernel: [<ffffffff81100a61>] ? swap_entry_free+0x7a/0xf3 Apr 7 09:33:30 dbnode kernel: [<ffffffff8111c239>] ? fget_light+0x34/0x73 Apr 7 09:33:30 dbnode kernel: [<ffffffff813b0fcb>] ? sockfd_lookup_light+0x20/0x58 Apr 7 09:33:30 dbnode kernel: [<ffffffff813b22cf>] sys_sendto+0x12f/0x171 Apr 7 09:33:30 dbnode kernel: [<ffffffff810a9d23>] ? audit_syscall_entry+0x103/0x12f Apr 7 09:33:30 dbnode kernel: [<ffffffff81011db2>] system_call_fastpath+0x16/0x1b > > I can't comment on how this may affect Mellanox Hardware but it seems like it > will work fine with Qib hardware. > > Ira > > > > > > Jason > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
