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Commit 5a804b92 authored by Jerry Zhang's avatar Jerry Zhang
Browse files

Use FUNCTIONFS_ENDPOINT_ALLOC_BUFFER ioctl to improve performance. 

The ioctl preallocates kernel buffers for the read/write syscalls,
reducing memory fragmentation and allowing for larger buffers,
as well as removing the kmalloc overhead.

Test: Manual
Change-Id: I9f5fef1b1625c1a2cda374541d8042f7e0ba78f5
parent 0da9804f

media/mtp/MtpFfsHandle.cpp

+23 −0
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ 
#define cpu_to_le16(x)  htole16(x)

#define cpu_to_le32(x)  htole32(x)



#define FUNCTIONFS_ENDPOINT_ALLOC       _IOR('g', 131, __u32)



namespace {



constexpr char FFS_MTP_EP_IN[] = "/dev/usb-ffs/mtp/ep1";
@@ -467,6 +469,24 @@ void MtpFfsHandle::close() { 
    mLock.unlock();

}



class ScopedEndpointBufferAlloc {

private:

    const int mFd;

    const unsigned int mAllocSize;

public:

    ScopedEndpointBufferAlloc(int fd, unsigned alloc_size) :

        mFd(fd),

        mAllocSize(alloc_size) {

        if (ioctl(mFd, FUNCTIONFS_ENDPOINT_ALLOC, static_cast<__u32>(mAllocSize)))

            PLOG(DEBUG) << "FFS endpoint alloc failed!";

    }



    ~ScopedEndpointBufferAlloc() {

        if (ioctl(mFd, FUNCTIONFS_ENDPOINT_ALLOC, static_cast<__u32>(0)))

            PLOG(DEBUG) << "FFS endpoint alloc reset failed!";

    }

};



/* Read from USB and write to a local file. */

int MtpFfsHandle::receiveFile(mtp_file_range mfr) {

    // When receiving files, the incoming length is given in 32 bits.
@@ -494,6 +514,7 @@ int MtpFfsHandle::receiveFile(mtp_file_range mfr) { 
    bool write = false;



    posix_fadvise(mfr.fd, 0, 0, POSIX_FADV_SEQUENTIAL | POSIX_FADV_NOREUSE);

    ScopedEndpointBufferAlloc(mBulkOut, mMaxRead);



    // Break down the file into pieces that fit in buffers

    while (file_length > 0 || write) {
@@ -609,6 +630,8 @@ int MtpFfsHandle::sendFile(mtp_file_range mfr) { 
    if (writeHandle(mBulkIn, data, packet_size) == -1) return -1;

    if (file_length == 0) return 0;



    ScopedEndpointBufferAlloc(mBulkIn, mMaxWrite);



    // Break down the file into pieces that fit in buffers

    while(file_length > 0) {

        if (read) {