Date: Wed, 19 Dec 2012 06:44:13 -0800 From: Matthew Jacob <mjacob@freebsd.org> To: freebsd-arch@freebsd.org Subject: Re: Unmapped I/O Message-ID: <50D1D2BD.80107@freebsd.org> In-Reply-To: <20121219135451.GU71906@kib.kiev.ua> References: <20121219135451.GU71906@kib.kiev.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
On 12/19/2012 5:54 AM, Konstantin Belousov wrote: > One of the known FreeBSD I/O path performance bootleneck is the > neccessity to map each I/O buffer pages into KVA. The problem is that > on the multi-core machines, the mapping must flush TLB on all cores, > due to the global mapping of the buffer pages into the kernel. This > means that buffer creation and destruction disrupts execution of all > other cores to perform TLB shootdown through IPI, and the thread > initiating the shootdown must wait for all other cores to execute and > report. > About time!
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?50D1D2BD.80107>