lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 6 Jan 2012 09:54:46 -0800 From: Mike Waychison <mikew@...gle.com> To: Rusty Russell <rusty@...tcorp.com.au> Cc: "Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, virtualization@...ts.linux-foundation.org Subject: Re: [RFC PATCH v1 2/2] virtio_net: Don't disable napi on low memory. On Wed, Jan 4, 2012 at 6:46 PM, Mike Waychison <mikew@...gle.com> wrote: > On Wed, Jan 4, 2012 at 4:31 PM, Rusty Russell <rusty@...tcorp.com.au> wrote: >> 4) You use the skb data for the linked list; use the skb head's list. What did you mean by this? I was under the impression that the ->next and ->prev fields in sk_buff were the first two elements specifically so that the pointer could be treated as a list_head. If it's the cast in particular that you have an objection with, I can easily change this to a singly linked list threaded through ->next if that's cleaner. >> >> Instead, here's how I think it should be done: ... > > This sounds reasonable to me. I'll see what I can muster together this week. > So I started implementing it the way you were mentioning, and ran into a problem with the original patchset. Currently the "mergeable" and "big" receive buffers use a private page free list (virtnet_info->pages) which has no synchronization itself. This means that the batched version can't use get_a_page() and give_pages() as is, which reduces the need to re-use the same alloc halves that I've split. Alternatives I can think of at this point: - pass in a flag to the allocators like "bool is_serial" that is true if we are serializing with napi, (which determines if we can much with vi->pages) or - not use the same allocators for the "mergeable" and "big" paths. The mergeable allocator in the non-serialized case reduces to alloc_page(), while the big allocator looks like a copy and paste that uses alloc_page instead of get_a_page(). Preferences? I'll code one of the two up and see what it looks like. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists