Date: Mon, 10 Oct 2016 10:46:27 -0700 From: John Baldwin <jhb@freebsd.org> To: Slawa Olhovchenkov <slw@zxy.spb.ru> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: Re: svn commit: r306661 - in stable/11/sys/dev/cxgbe: . tom Message-ID: <1660024.uzJn2AtV1k@ralph.baldwin.cx> In-Reply-To: <20161010110901.GH6177@zxy.spb.ru> References: <201610032315.u93NFiHE057529@repo.freebsd.org> <20161010110901.GH6177@zxy.spb.ru>
next in thread | previous in thread | raw e-mail | index | archive | help
On Monday, October 10, 2016 02:09:01 PM Slawa Olhovchenkov wrote: > On Mon, Oct 03, 2016 at 11:15:44PM +0000, John Baldwin wrote: > > > Author: jhb > > Date: Mon Oct 3 23:15:44 2016 > > New Revision: 306661 > > URL: https://svnweb.freebsd.org/changeset/base/306661 > > > > Log: > > MFC 303405: Add support for zero-copy aio_write() on TOE sockets. > > > > AIO write requests for a TOE socket on a Chelsio T4+ adapter can now > > DMA directly from the user-supplied buffer. This is implemented by > > wiring the pages backing the user-supplied buffer and queueing special > > mbufs backed by raw VM pages to the socket buffer. The TOE code > > recognizes these special mbufs and builds a sglist from the VM page > > array associated with the mbuf when queueing a work request to the TOE. > > > > Because these mbufs do not have an associated virtual address, m_data > > is not valid. Thus, the AIO handler does not invoke sosend() directly > > for these mbufs but instead inlines portions of sosend_generic() and > > tcp_usr_send(). > > > > An aiotx_buffer structure is used to describe the user buffer (e.g. > > it holds the array of VM pages and a reference to the AIO job). The > > special mbufs reference this structure via m_ext. Note that a single > > job might be split across multiple mbufs (e.g. if it is larger than > > the socket buffer size). The 'ext_arg2' member of each mbuf gives an > > offset relative to the backing aiotx_buffer. The AIO job associated > > with an aiotx_buffer structure is completed when the last reference to > > the structure is released. > > > > Zero-copy aio_write()'s for connections associated with a given > > adapter can be enabled/disabled at runtime via the > > 'dev.t[45]nex.N.toe.tx_zcopy' sysctl. > > > > Sponsored by: Chelsio Communications > > Do you have any public available application patches for support this? > May be nginx? Applications need to use aio_read(), ideally with at least 2 buffers (so queue two reads, then when a read completes, consume the data and do the next read). I'm not sure nginx will find this but so useful as web servers tend to send a lot more data than they receive. The only software I have patched explicitly for this is netperf. -- John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?1660024.uzJn2AtV1k>