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You say in your bench that Dokan support does not support memory mapped files but it does as I can see with fsx (memory mapped read/write enabled) running on th

• billziss 10y ago
  > You say in your bench that Dokan support does not support memory mapped files but it does as I can see with fsx (memory mapped read/write enabled) It was me that ported FSX to windows so I am quite familiar with this test. Here is the code that fails in fsbench: Mapping = CreateFileMappingW(Handle, 0, PAGE_READWRITE, 0, FileSize, 0); I would be happy if you explained to me how Dokany/MEMFS fails this code. > You add lock (that will slow down the result) on Dokan implementation only https://github.com/billziss-gh/memfs-dokany/commit/03ebaebb1.. https://github.com/billziss-gh/memfs-dokany/commit/03ebaebb1.... The lock exists on WinFsp/MEMFS. It is just taken in a different place: https://github.com/billziss-gh/winfsp/blob/master/src/dll/fsop.c#L60 > After that you see that dokan is faster to list files (https://github.com/billziss-gh/winfsp/commit/595a77bd2e45347... https://github.com/billziss-gh/winfsp/commit/595a77bd2e45347...) You improve YOUR MEMFS winfsp implementation https://github.com/billziss-gh/winfsp/commit/f7ca9f05221040a.. https://github.com/billziss-gh/winfsp/commit/f7ca9f05221040a.... but not on dokan ? The WinFsp/MEMFS had indeed a problem which I fixed, but it was not WinFsp related (it was MEMFS related - aka my test user mode file system). I attempted to apply the same fix to Dokany/MEMFS, but I could not because Dokany does not pass an Offset parameter to its FindFiles operation. > You also improve memory allocation on winfsp memfs implementation and again not on dokan https://github.com/billziss-gh/winfsp/commit/d12234bb01b3620.. https://github.com/billziss-gh/winfsp/commit/d12234bb01b3620.... Actually that is incorrect. https://github.com/billziss-gh/memfs-dokany/blob/master/memfs-dokany.cpp#L88 > My point is even if Winfsp is fast on your test with an unfair FS, I am pretty sure there is not difference with real applications on a non-virtual machine. No. WinFsp is faster, because it is faster. Feel free to send me any pull requests that you want for Dokany/MEMFS and I will incorporate them into the project and re-run the tests.
  • IsBisu 10y ago
    >Mapping = CreateFileMappingW(Handle, 0, PAGE_READWRITE, 0, FileSize, 0); So it is more a "case" not handled by dokan rather that all memory mapped not handled ? Is this made in purpose just to remove dokan from the bench ? >The lock exists on WinFsp/MEMFS. It is just taken in a different place: It changes nothing on what I said. You added it on dokan side without reason and not on winfsp memfs. >send me any pull requests that you want for Dokany/MEMFS A pull request will not change that a real application on a non-virtual machine will not see the difference.
    • billziss 10y ago
      > >Mapping = CreateFileMappingW(Handle, 0, PAGE_READWRITE, 0, FileSize, 0); > > So it is more a "case" not handled by dokan rather that all memory mapped not handled ? Is this made in purpose just to remove dokan from the bench ? I do not understand this. Are you familiar with how memory mapping works on Windows? CreateFileMappingW is it. If that API fails you do not have memory mapping. Furthermore I challenge you to show me how Dokany/MEMFS makes this API fail. If you find such an issue I promise to fix it and re-run the tests. >The lock exists on WinFsp/MEMFS. It is just taken in a different place: It changes nothing on what I said. You added it on dokan side without reason and not on winfsp memfs. I added it on Dokan side, because I needed to protect the Dokany/MEMFS data structures against corruption. On the WinFsp side this lock is taken automatically as a convenience (although one can remove it if the file system can cope by using a custom "operation guard" (FspFileSystemSetOperationGuard) -- it is not needed for WinFsp operation). The exact same lock is taken on both sides. There is no unfair advantage to WinFsp. If you design a file system that takes no locks and works on both WinFsp and Dokany, I will be happy to run the tests against that file system. > A pull request will not change that a real application on a non-virtual machine will not see the difference. All the "real application" has to do is to open a file and issues some I/O. Just because Dokany does not cache I/O it will be 9x-10x slower than WinFsp.
      • billziss 10y ago
        > The exact same lock is taken on both sides. There is no unfair advantage to WinFsp. If you design a file system that takes no locks and works on both WinFsp and Dokany, I will be happy to run the tests against that file system. Alternatively you can show me that there is a lock already taken within Dokany for this purpose (protection of the data structures of the user mode file system) and I will be happy to remove the lock and rerun the tests.