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Commit 91573601 authored by Jeff Sharkey's avatar Jeff Sharkey
Browse files

Switch to static warning threshold when adopting. 

See rationale and details in inline comment block.

Test: adopt slow and fast SD cards
Bug: 29990216
Change-Id: I927d683db5e43216ee0837290ee4ca23a55a5dbb
parent 9574fb80

src/com/android/settings/deviceinfo/StorageWizardFormatProgress.java

+34 −11
Original line number Diff line number Diff line
@@ -88,7 +88,6 @@ public class StorageWizardFormatProgress extends StorageWizardBase { 


        private volatile int mProgress = 20;



        private volatile long mInternalBench;

        private volatile long mPrivateBench;



        @Override
@@ -100,11 +99,9 @@ public class StorageWizardFormatProgress extends StorageWizardBase { 
                    storage.partitionPrivate(activity.mDisk.getId());

                    publishProgress(40);



                    mInternalBench = storage.benchmark(null);

                    publishProgress(60);



                    final VolumeInfo privateVol = activity.findFirstVolume(VolumeInfo.TYPE_PRIVATE);

                    mPrivateBench = storage.benchmark(privateVol.getId());

                    mPrivateBench /= 1000000;



                    // If we just adopted the device that had been providing

                    // physical storage, then automatically move storage to the
@@ -152,13 +149,39 @@ public class StorageWizardFormatProgress extends StorageWizardBase { 
            }



            if (activity.mFormatPrivate) {

                final float pct = (float) mInternalBench / (float) mPrivateBench;

                Log.d(TAG, "New volume is " + pct + "x the speed of internal");



                // To help set user expectations around device performance, we

                // warn if the adopted media is 0.25x the speed of internal

                // storage or slower.

                if (Float.isNaN(pct) || pct < 0.25) {

                // When the adoptable storage feature originally launched, we

                // benchmarked both internal storage and the newly adopted

                // storage and we warned if the adopted device was less than

                // 0.25x the speed of internal. (The goal was to help set user

                // expectations and encourage use of devices comparable to

                // internal storage performance.)



                // However, since then, internal storage has started moving from

                // eMMC to UFS, which can significantly outperform adopted

                // devices, causing the speed warning to always trigger. To

                // mitigate this, we've switched to using a static threshold.



                // The static threshold was derived by running the benchmark on

                // a wide selection of SD cards from several vendors; here are

                // some 50th percentile results from 20+ runs of each card:



                // 8GB C4 40MB/s+: 3282ms

                // 16GB C10 40MB/s+: 1881ms

                // 32GB C10 40MB/s+: 2897ms

                // 32GB U3 80MB/s+: 1595ms

                // 32GB C10 80MB/s+: 1680ms

                // 128GB U1 80MB/s+: 1532ms



                // Thus a 2000ms static threshold strikes a reasonable balance

                // to help us identify slower cards. Users can still proceed

                // with these slower cards; we're just showing a warning.



                // The above analysis was done using the "r1572:w1001:s285"

                // benchmark, and it should be redone any time the benchmark

                // changes.



                Log.d(TAG, "New volume took " + mPrivateBench + "ms to run benchmark");

                if (mPrivateBench > 2000) {

                    final SlowWarningFragment dialog = new SlowWarningFragment();

                    dialog.showAllowingStateLoss(activity.getFragmentManager(), TAG_SLOW_WARNING);

                } else {