* Re: [PATCH v5 1/2] io_uring: minor io_cqring_wait() optimization [not found] ` <[email protected]> @ 2022-03-09 23:43 ` Jens Axboe 0 siblings, 0 replies; 2+ messages in thread From: Jens Axboe @ 2022-03-09 23:43 UTC (permalink / raw) To: Olivier Langlois, Pavel Begunkov; +Cc: Hao Xu, io-uring, linux-kernel On 3/8/22 10:36 PM, Olivier Langlois wrote: > On Tue, 2022-03-08 at 17:54 -0700, Jens Axboe wrote: >> On 3/8/22 3:17 PM, Olivier Langlois wrote: >>> Move up the block manipulating the sig variable to execute code >>> that may encounter an error and exit first before continuing >>> executing the rest of the function and avoid useless computations >> >> I don't think this is worthwhile doing. If you're hitting an error >> in any of them, it's by definition not the fast path. >> > Well, by itself it is not a big improvement but it is still an > improvement. > > but most importantly, it has to be considered in the context of the > current patchset because in patch #2, the following step is to > > 1. acquire the napi spin lock > 2. splice the context napi list into a local one. > 3. release the lock > > If this patch is not in place before patch #2, you would need undo all > that before returning from the sig block which would make the function > bigger when all that is completely avoidable by accepting this patch... > > Both patches were together in v1 but I decided to break them apart > thinking that this was the right thing to do... Yeah ok, it does make sense in the context of patch 2. Thanks! -- Jens Axboe ^ permalink raw reply [flat|nested] 2+ messages in thread
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* Re: [PATCH v5 0/2] io_uring: Add support for napi_busy_poll [not found] ` <[email protected]> @ 2022-03-09 23:44 ` Jens Axboe 0 siblings, 0 replies; 2+ messages in thread From: Jens Axboe @ 2022-03-09 23:44 UTC (permalink / raw) To: Olivier Langlois, Pavel Begunkov; +Cc: Hao Xu, io-uring, linux-kernel On 3/8/22 10:47 PM, Olivier Langlois wrote: > On Tue, 2022-03-08 at 17:54 -0700, Jens Axboe wrote: >> On 3/8/22 3:17 PM, Olivier Langlois wrote: >>> The sqpoll thread can be used for performing the napi busy poll in >>> a >>> similar way that it does io polling for file systems supporting >>> direct >>> access bypassing the page cache. >>> >>> The other way that io_uring can be used for napi busy poll is by >>> calling io_uring_enter() to get events. >>> >>> If the user specify a timeout value, it is distributed between >>> polling >>> and sleeping by using the systemwide setting >>> /proc/sys/net/core/busy_poll. >> >> I think we should get this queued up, but it doesn't apply to >> for-5.18/io_uring at all. I can fix it up, but just curious what you >> tested against? >> > Hi Jens, > > I did wrote the patch from > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > > My testing systems are based on 5.16. I have backported the patch and > compiled 5.16.12 with the patch for my testing. > > sorry if I didn't use the right repo... Generally, since the patch is for 5.18, you'd want to base it on my for-5.18/io_uring branch as then it would apply on top of what is already pending. But I'll see if I can shoe horn it, unfortunately we'll hit a merge error but it'll be minor. -- Jens Axboe ^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2022-03-09 23:44 UTC | newest] Thread overview: 2+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- [not found] <[email protected]> [not found] ` <84513f7cc1b1fb31d8f4cb910aee033391d036b4.1646777484.git.olivier@trillion01.com> [not found] ` <[email protected]> [not found] ` <[email protected]> 2022-03-09 23:43 ` [PATCH v5 1/2] io_uring: minor io_cqring_wait() optimization Jens Axboe [not found] ` <[email protected]> [not found] ` <[email protected]> 2022-03-09 23:44 ` [PATCH v5 0/2] io_uring: Add support for napi_busy_poll Jens Axboe
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