Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 2 Jan 2023 10:44:06 +0100 | Subject | Re: [PATCH v2 17/21] block, blksnap: snapshot image block device | From | Sergei Shtepa <> |
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On 1/1/23 08:18, Hillf Danton wrote: > Subject: > Re: [PATCH v2 17/21] block, blksnap: snapshot image block device > From: > Hillf Danton <hdanton@sina.com> > Date: > 1/1/23, 08:18 > > To: > Sergei Shtepa <sergei.shtepa@veeam.com> > CC: > "axboe@kernel.dk" <axboe@kernel.dk>, "corbet@lwn.net" <corbet@lwn.net>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> > > > This is the first time you've received an email from this sender > hdanton@sina.com, please exercise caution when clicking on links or opening > attachments. > > > On 9 Dec 2022 15:23:27 +0100 Sergei Shtepa > > Provides the operation of block devices of snapshot images. Read and > > write operations are redirected to the regions of difference blocks for > > block device (struct diff_area). > > > > Signed-off-by: Sergei Shtepa > > --- > > Thanks for your patchset.
Thanks for the review.
> > > +static int snapimage_kthread_worker_fn(void *param) > > +{ > > + struct snapimage *snapimage = param; > > + struct bio *bio; > > + int ret = 0; > > + > > + while (!kthread_should_stop()) { > > + bio = get_bio_from_queue(snapimage); > > + if (!bio) { > > + schedule_timeout_interruptible(HZ / 100); > > + continue; > > + } > > Given the wake_up_process() below, s$HZ / 100$HZ * 1000$ to avoid > unnecessary wakeups [1]. > > And because of no signal handling added, use schedule_timeout_idle() instead.
Yes, this function will be rewritten to eliminate unnecessary wake-ups. The code that Christoph proposed in the letter at Dec 15 should work well.
> > [1] > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F20210419085027.761150-2-elver%40google.com%2F&data=05%7C01%7Csergei.shtepa%40veeam.com%7C765d591d47ad4d93857208daebc92508%7Cba07baab431b49edadd7cbc3542f5140%7C1%7C1%7C638081546440884849%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=rbINOq7m31DFhjHLnQKFHQuoWB64ZhmnWbAVLuNwv7w%3D&reserved=0 > > > + > > + snapimage_process_bio(snapimage, bio); > > + } > > + > > + while ((bio = get_bio_from_queue(snapimage))) > > + snapimage_process_bio(snapimage, bio); > > + > > + return ret; > > +} > > + > > +static void snapimage_submit_bio(struct bio *bio) > > +{ > > + struct snapimage *snapimage = bio->bi_bdev->bd_disk->private_data; > > + gfp_t gfp = GFP_NOIO; > > + > > + if (bio->bi_opf & REQ_NOWAIT) > > + gfp |= GFP_NOWAIT; > > + if (snapimage->is_ready) { > > + spin_lock(&snapimage->queue_lock); > > + bio_list_add(&snapimage->queue, bio); > > + spin_unlock(&snapimage->queue_lock); > > + > > + wake_up_process(snapimage->worker); > > + } else > > + bio_io_error(bio); > > +} >
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