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Commit b631927c authored by Isaac J. Manjarres's avatar Isaac J. Manjarres
Browse files

Improve lost RAM calculation by removing kernel driver CMA allocations 



CMA memory can be in one of the following four states at any given
point in time:

1. Free, in which case it is already accounted for when computing
   lost RAM, since lost RAM subtracts free memory from total memory.

2. Allocated to userspace processes, in which case the memory has
   already been accounted for when computing lost RAM as part of the
   total PSS value that is computed.

3. Allocated for storing compressed memory (ZRAM) on Android kernels.
   This is already accounted for in the lost RAM calculation, since
   the calculation includes the memory consumed by ZRAM.

4. Allocated to a kernel driver, in which case the memory is not
   accounted for with the current kernel memory usage calculation.
   This memory ends up being counted as lost RAM.

Android exposes an interface that can be used to calculate how much
memory kernel drivers are allocating through CMA. Therefore, use
this interface to calculate this value, and improve the lost RAM
calculation.

Bug: 371518137
Bug: 228238851
Change-Id: Ia37ffbf861ac01708d90a10f0c76df745a33597d
Signed-off-by: default avatarIsaac J. Manjarres <isaacmanjarres@google.com>
parent fda96163

services/core/java/com/android/server/am/ActivityManagerService.java

+43 −1
Original line number Diff line number Diff line
@@ -13144,6 +13144,28 @@ public class ActivityManagerService extends IActivityManager.Stub 
                }

            }













            final long kernelCmaUsage = Debug.getKernelCmaUsageKb();













            if (kernelCmaUsage >= 0) {













                pw.print("      Kernel CMA: ");













                pw.println(stringifyKBSize(kernelCmaUsage));













                // CMA memory can be in one of the following four states:













                //













                // 1. Free, in which case it is accounted for as part of MemFree, which













                //    is already considered in the lostRAM calculation below.













                //













                // 2. Allocated as part of a userspace allocated, in which case it is













                //    already accounted for in the total PSS value that was computed.













                //













                // 3. Allocated for storing compressed memory (ZRAM) on Android kernels.













                //    This is accounted for by calculating the amount of memory ZRAM













                //    consumes and including it in the lostRAM calculuation.













                //













                // 4. Allocated by a kernel driver, in which case, it is currently not













                //    attributed to any term that has been derived thus far. Since the













                //    allocations come from a kernel driver, add it to kernelUsed.













                kernelUsed += kernelCmaUsage;













            }



























             // Note: ION/DMA-BUF heap pools are reclaimable and hence, they are included as part of















             // memInfo.getCachedSizeKb().















            final long lostRAM = memInfo.getTotalSizeKb()










@@ -13661,12 +13683,32 @@ public class ActivityManagerService extends IActivityManager.Stub













                proto.write(MemInfoDumpProto.CACHED_KERNEL_KB, memInfo.getCachedSizeKb());















                proto.write(MemInfoDumpProto.FREE_KB, memInfo.getFreeSizeKb());















            }













            // CMA memory can be in one of the following four states:













            //













            // 1. Free, in which case it is accounted for as part of MemFree, which













            //    is already considered in the lostRAM calculation below.













            //













            // 2. Allocated as part of a userspace allocated, in which case it is













            //    already accounted for in the total PSS value that was computed.













            //













            // 3. Allocated for storing compressed memory (ZRAM) on Android Kernels.













            //    This is accounted for by calculating hte amount of memory ZRAM













            //    consumes and including it in the lostRAM calculation.













            //













            // 4. Allocated by a kernel driver, in which case, it is currently not













            //    attributed to any term that has been derived thus far, so subtract













            //    it from lostRAM.













            long kernelCmaUsage = Debug.getKernelCmaUsageKb();













            if (kernelCmaUsage < 0) {













                kernelCmaUsage = 0;













            }















            long lostRAM = memInfo.getTotalSizeKb()















                    - (ss[INDEX_TOTAL_PSS] - ss[INDEX_TOTAL_SWAP_PSS])















                    - memInfo.getFreeSizeKb() - memInfo.getCachedSizeKb()















                    // NR_SHMEM is subtracted twice (getCachedSizeKb() and getKernelUsedSizeKb())















                    + memInfo.getShmemSizeKb()













                    - memInfo.getKernelUsedSizeKb() - memInfo.getZramTotalSizeKb();













                    - memInfo.getKernelUsedSizeKb() - memInfo.getZramTotalSizeKb()













                    - kernelCmaUsage;















            proto.write(MemInfoDumpProto.USED_PSS_KB, ss[INDEX_TOTAL_PSS] - cachedPss);















            proto.write(MemInfoDumpProto.USED_KERNEL_KB, memInfo.getKernelUsedSizeKb());















            proto.write(MemInfoDumpProto.LOST_RAM_KB, lostRAM);