Steve Graegert wrote: > On 4/5/06, Glynn Clements <glynn@xxxxxxxxxxxxxxxxxx> wrote: > > Rebelde wrote: > > > On Windows XP I can write directly to disk whitout cache write using > > > the CreateFile function with FILE_FLAG_WRITE_THROUGH. Could someone > > > tell me how to make this on Linux? > > > > Pass the O_SYNC flag to open(). This will cause write() calls to block > > until the data has been sent to the drive. > > > > The O_DIRECT flag suggested by Steve is probably overkill. It requires > > that the buffer start address, buffer size and file offset are all > > multiples of the filesystem's block size, and only works on some > > filesystems. > > Well, the O_SYNC flag causes, i.e. write(2), to block until the data > has been physically written to disk, but it does not prevent the C > library/kernel from caching the bytes. O_DIRECT, on the other hand, > circumvents the caching mechanisms and allows for raw access, although > it may degrade performance. Or increase performance because dcache costs dear cpu-cycles? Thanks! -- Al - : send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
