lots of 'job not found' from pool on Ethash compared to other miners

[aleqx]

Ubuntu 16.04, Nvidia 450.57, Cuda 10.2, both 0.19.1 and 0.19.3 (which says it reduced rejected shares)

I see a high rejected share rate on pretty much all the GPUs, sometimes as high as 7%, all of them with Job not found coming from the pool. Other miners (phoenix, claymore, ethminer, gminer) have <1% and I can tell that in their case it is legit, because it happens right after getting a new job from the pool (so the pool considers it stale ... it shouldn't but still, that's another story).

The worst is on Nicehash.

Basically, whatever 0-1% speed increase your miner has over other miners, it gets trumped by this high share reject rate ...

I have a hunch that something in your code submit the wrong job hash in cases where multiple shares are submitted almost at the same time (shares found very quickly in sequence) -- I tcpdump'ed it to have a look. The pool sometimes doesn't have time to ack each share in sequence. Strangely, however, it's not always the case: sometimes two shares submitted almost at the same time (few ms apart) does get two result:true acks from the pool, whereas other times it gets only one ack and a job not found. The two shares do have different job hashes, and different json-rpc message ids.

Something you may want to look into. I don't know your code (I know ethminer's)

[aleqx]

An example from Nicehash (not even 1h of mining).

209/224 = 6.3% rejected. In the previous session it was close to 10%. I'm aware of how Nicehash works - there was no change of DAG or coin here during the past 20 minutes, yet there were plenty of rejects.

[...]
20201212 16:27:36 [ OK ] 208/222 - 334.94 MH/s, 110ms ... GPU #5
20201212 16:27:38 [ OK ] 209/223 - 334.95 MH/s, 175ms ... GPU #4
20201212 16:27:41 Mining at daggerhashimoto.eu.nicehash.com:3353, diff: 2.89 Gh
20201212 16:27:41 GPU #0: GTX 1080 Ti - 48.07 MH/s, 37/41 R:9.76%
20201212 16:27:41 GPU #1: GTX 1080 Ti - 47.59 MH/s, 26/29 R:10.34%
20201212 16:27:41 GPU #2: GTX 1080 Ti - 47.28 MH/s, 25/27 R:7.41%
20201212 16:27:41 GPU #3: GTX 1080 Ti - 48.71 MH/s, 40/41 R:2.44%
20201212 16:27:41 GPU #4: GTX 1080 Ti - 44.34 MH/s, 19/20 R:5%
20201212 16:27:41 GPU #5: GTX 1080 Ti - 49.35 MH/s, 32/35 R:8.57%
20201212 16:27:41 GPU #6: GTX 1080 Ti - 49.60 MH/s, 30/30 R:0%
20201212 16:27:41 Hashrate: 334.93 MH/s, Shares/min: 3.741 (Avr. 4.257) R: 6.278%
20201212 16:27:41 Uptime: 49 mins 8 secs | Algo: ethash | T-Rex v0.19.3
20201212 16:27:41 WD: 49 mins 10 secs, shares 209/223
20201212 16:27:55 [FAIL] 209/224 - Job not found., 320ms ... GPU #1
20201212 16:27:56 [ OK ] 210/225 - 334.96 MH/s, 88ms ... GPU #1
[...]

[cirlama]

same on win 10 with Nicehash, v0.19.5, tested on gtx 1080 ti & RTX 3070

[Alchnemesis]

It happens to me as well when mining on NiceHash, Is that related to NiceHash itself? Or could be the card OC problem?

[kyfami]

Still having this issue as of 01/23/21 NH will tell you it's because of your overclock, even though it still does it on stock settings.

[brimnac1022]

Same issues when using a 1080 in Linux.