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Commit de43e5f1 authored by Shai Barack's avatar Shai Barack
Browse files

Make writing Bitmap to ashmem faster 

Write to memfd instead.
Avoid mmap+memcpy+munmap.

See b/407422742 for rationale, research, and benchmark results.

Bug: 407422742
Flag: com.android.graphics.hwui.flags.bitmap_use_memfd
Test: BitmapPerfTest
Change-Id: I64c6850721004f3f6ec71964169230f8c9828e16
parent d6941c1e

libs/hwui/aconfig/hwui_flags.aconfig

+8 −0
Original line number Diff line number Diff line
@@ -211,3 +211,11 @@ flag { 
  description: "Whether to parcel implicit copies of bitmaps to ashmem as immutable"

  bug: "400807118"

}



flag {

  name: "bitmap_use_memfd"

  namespace: "system_performance"

  description: "Whether to parcel implicit copies of bitmaps to memfd instead of ashmem"

  bug: "400807118"

  is_fixed_read_only: true

}
 
 No newline at end of file

libs/hwui/jni/Bitmap.cpp

+42 −12
Original line number Diff line number Diff line
@@ -5,11 +5,15 @@ 
#ifdef __linux__

#include <com_android_graphics_hwui_flags.h>

#endif

#include <fcntl.h>

#include <hwui/Bitmap.h>

#include <hwui/Paint.h>

#include <inttypes.h>

#include <renderthread/RenderProxy.h>

#include <string.h>

#include <sys/mman.h>

#include <sys/syscall.h>

#include <unistd.h>



#include <memory>
@@ -688,7 +692,31 @@ static binder_status_t writeBlob(AParcel* parcel, uint64_t bitmapId, const SkBit 
        // Create new ashmem region with read/write priv

        auto ashmemId = Bitmap::getAshmemId("writeblob", bitmapId,

                                            bitmap.width(), bitmap.height(), size);

        base::unique_fd fd(ashmem_create_region(ashmemId.c_str(), size));

        base::unique_fd fd;



        if (com::android::graphics::hwui::flags::bitmap_use_memfd()) {

            fd.reset(syscall(__NR_memfd_create, ashmemId.c_str(), MFD_CLOEXEC | MFD_ALLOW_SEALING));

            if (fd.get() < 0) {

                return STATUS_NO_MEMORY;

            }



            ssize_t written = write(fd.get(), data, size);

            if (written != size) {

                return STATUS_NO_MEMORY;

            }



            if (fcntl(fd, F_ADD_SEALS,

                        // Disallow growing / shrinking

                        F_SEAL_GROW | F_SEAL_SHRINK

                        // If immutable, disallow writing

                        | (immutable ? F_SEAL_WRITE : 0)

                        // Seal the seals 🦭

                        | F_SEAL_SEAL) == -1) {

                return STATUS_UNKNOWN_ERROR;

            }



        } else {

            fd.reset(ashmem_create_region(ashmemId.c_str(), size));

            if (fd.get() < 0) {

                return STATUS_NO_MEMORY;

            }
@@ -705,6 +733,8 @@ static binder_status_t writeBlob(AParcel* parcel, uint64_t bitmapId, const SkBit 
            if (immutable && ashmem_set_prot_region(fd.get(), PROT_READ) < 0) {

                return STATUS_UNKNOWN_ERROR;

            }

        }



        // Workaround b/149851140 in AParcel_writeParcelFileDescriptor

        int rawFd = fd.release();

        error = writeBlobFromFd(parcel, size, rawFd);