Mass-storage performance enhancements - #7578
Open
P33M wants to merge 2 commits into
Open
Conversation
This quirk has a negative impact on most USB mass-storage devices. The description of the feature in the databook is conflated with a case where parkmode performs badly with specific devices, but doesn't assign importance to this statement: "When park mode is disabled, pipelining of multiple packets is disabled and instead one packet at a time is requested by the scheduler." Removing the pipelining causes inter-transaction latency of the order of 4us when a single HS bulk endpoint is being serviced. This drops USB mass-storage sequential performance by 20%. RP1 has separate bus instances for each USB2 port, so the multi-device case that theoretically suffers is even less likely to occur. In raspberrypi#5892 this feature was disabled at the recommendation of Synopsys, not through a requirement to fix an interop bug with a device in the field. So turn "park mode" back on for HS. Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
Apply the higher USB3 limit to USB3 devices connected to USB2 ports, detectable through the existence of a SuperSpeed companion descriptor. For 16K page platforms, use 192 in preference to 240 as this breaks transfers on a 64-sector boundary instead of 32. Middle-of-the-range devices show a modest sequential speed increase with 64s alignment. Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
See #7545 (comment) for rationale.
Increasing nominated USB2 devices' max_sectors limit (e.g. linux UMS gadgets) should be handled by udev rulesets.