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 PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 31 May 2022 21:27:35 +0200 From: Arnd Bergmann <arnd@...db.de> To: Allen Pais <apais@...ux.microsoft.com> Cc: Arnd Bergmann <arnd@...db.de>, Vinod Koul <vkoul@...nel.org>, Linus Walleij <linus.walleij@...aro.org>, Vincent Guittot <vincent.guittot@...aro.org>, olivier.dautricourt@...lia.com, Stefan Roese <sr@...x.de>, Kees Cook <keescook@...omium.org>, linux-hardening@...r.kernel.org, Ludovic Desroches <ludovic.desroches@...rochip.com>, Tudor Ambarus <tudor.ambarus@...rochip.com>, Florian Fainelli <f.fainelli@...il.com>, Ray Jui <rjui@...adcom.com>, Scott Branden <sbranden@...adcom.com>, bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>, Nicolas Saenz Julienne <nsaenz@...nel.org>, Paul Cercueil <paul@...pouillou.net>, Eugeniy.Paltsev@...opsys.com, Gustavo Pimentel <gustavo.pimentel@...opsys.com>, Viresh Kumar <vireshk@...nel.org>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Leo Li <leoyang.li@....com>, zw@...kernel.org, Zhou Wang <wangzhou1@...ilicon.com>, Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, Sean Wang <sean.wang@...iatek.com>, Matthias Brugger <matthias.bgg@...il.com>, Andreas Färber <afaerber@...e.de>, Manivannan Sadhasivam <mani@...nel.org>, Logan Gunthorpe <logang@...tatee.com>, Sanjay R Mehta <sanju.mehta@....com>, Daniel Mack <daniel@...que.org>, Haojian Zhuang <haojian.zhuang@...il.com>, Robert Jarzmik <robert.jarzmik@...e.fr>, Andy Gross <agross@...nel.org>, Bjorn Andersson <bjorn.andersson@...aro.org>, Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, green.wan@...ive.com, Orson Zhai <orsonzhai@...il.com>, Baolin Wang <baolin.wang7@...il.com>, Lyra Zhang <zhang.lyra@...il.com>, Patrice CHOTARD <patrice.chotard@...s.st.com>, Chen-Yu Tsai <wens@...e.org>, Jernej Škrabec <jernej.skrabec@...il.com>, Samuel Holland <samuel@...lland.org>, dmaengine@...r.kernel.org, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: [RFC 1/1] drivers/dma/*: replace tasklets with workqueue On Tue, May 31, 2022 at 8:19 PM Allen Pais <apais@...ux.microsoft.com> wrote: > >>> That is a good idea, lot of drivers are waiting for completion which can > >>> be signalled from hardirq, this would also reduce the hops we have and > >>> help improve latency a bit. On the downside, some controllers provide > >>> error information, which would need to be dealt with. > >> > >> > >> I am not an expert in dma subsystem, but by using completion from > >> Hardirq context be a concern? Especially with latency. > > > > I don't see how: to the task waiting for the completion, there should > > be no difference, and for the irq handler sending it, it just avoids > > a few cycles going into softirq context. > > Thanks for clarification. > > If I have understood it correctly, your suggestion is to move the current > Callback mechanism out to dmaengine as a generic helper function > And introduce completion in dma_async_tx_descriptor to handle what > Tasklets currently do. Right: around half the callbacks are a trivial version that does nothing other than calling complete(), so these will benefit from skipping the softirq, while the others still need the callback. Arnd
Powered by blists - more mailing lists