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On Monday, October 8, 2012 10:20:06 AM UTC+1, Mike wrote: > > Hi Everyone, > I am working on improving the MTP write performance of devices in general. > I came across this code in kernel/fs/sync.c > 178<http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=fs/sync.c;h=14eefeb44636bd1e24240ae09fe0dd046ed013fa;hb=0e51793e162ca432fc5f04178cf82b80a92c2659#l178>int > vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) > 179<http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=fs/sync.c;h=14eefeb44636bd1e24240ae09fe0dd046ed013fa;hb=0e51793e162ca432fc5f04178cf82b80a92c2659#l179>{ > 180<http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=fs/sync.c;h=14eefeb44636bd1e24240ae09fe0dd046ed013fa;hb=0e51793e162ca432fc5f04178cf82b80a92c2659#l180> > if (!file->f_op || !file->f_op->fsync) > 181<http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=fs/sync.c;h=14eefeb44636bd1e24240ae09fe0dd046ed013fa;hb=0e51793e162ca432fc5f04178cf82b80a92c2659#l181> > return -EINVAL; > 182<http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=fs/sync.c;h=14eefeb44636bd1e24240ae09fe0dd046ed013fa;hb=0e51793e162ca432fc5f04178cf82b80a92c2659#l182> > return file->f_op->fsync(file, start, end, datasync); > 183<http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=fs/sync.c;h=14eefeb44636bd1e24240ae09fe0dd046ed013fa;hb=0e51793e162ca432fc5f04178cf82b80a92c2659#l183>} > 184<http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=fs/sync.c;h=14eefeb44636bd1e24240ae09fe0dd046ed013fa;hb=0e51793e162ca432fc5f04178cf82b80a92c2659#l184>EXPORT_SYMBOL(vfs_fsync_range); > > can someone point out what happens if I disable this code, as I see good > improvement in performance if I disable this. > > Also this code has been changed in Samung's Kernel code > int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int > datasync) { struct address_space *mapping = file->f_mapping; int err, ret; > if (!file->f_op || !file->f_op->fsync) { ret = -EINVAL; goto out; } ret = > filemap_write_and_wait_range(mapping, start, end); /* * We need to protect > against concurrent writers, which could cause * livelocks in > fsync_buffers_list(). */ mutex_lock(&mapping->host->i_mutex); err = > file->f_op->fsync(file, datasync); if (!ret) ret = err; > mutex_unlock(&mapping->host->i_mutex); out: return ret; } > > Can anyone point out what the additional code is doing and why. (In case > you have seen this) > Also please suggest any other option to improve MTP write performance > > Thanks for your help > Mike > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
