[PATCH] D35200: Don't use mmap on Windows
yvvan abandoned this revision. yvvan added a comment. It was the wrong direction https://reviews.llvm.org/D35200 ___ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D35200: Don't use mmap on Windows
joerg added a comment. The primary reason for using mmap is not so much performance, but reduced memory foot print. https://reviews.llvm.org/D35200 ___ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D35200: Don't use mmap on Windows
ilya-biryukov added a comment. In https://reviews.llvm.org/D35200#844132, @yvvan wrote: > The files might also be removed. > I checked that with qtcreator from git. Switching to the different branch > started reparse of some files. > When I frequently switched branches back and forth I got lock issues. With > mmap turned off this did not happen. Renaming/removing memory mapped files also works fine. What were those 'lock issues' specifically? `MemoryBuffer` code that uses the function you're changing seems to be doing the right thing by always allowing shared file access. We definitely need a test case that realiably reproduces your issue. https://reviews.llvm.org/D35200 ___ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D35200: Don't use mmap on Windows
yvvan added a comment. The files might also be removed. I checked that with qtcreator from git. Switching to the different branch started reparse of some files. When I frequently switched branches back and forth I got lock issues. With mmap turned off this did not happen. https://reviews.llvm.org/D35200 ___ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D35200: Don't use mmap on Windows
ilya-biryukov added a comment. This looks strange. AFAIK, memory mapping files in Windows does no 'locking' by itself. I've just written a small program to check that it's possible to modify the file, memory-mapped using Win32 API. What is specific problem you ran into? https://reviews.llvm.org/D35200 ___ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D35200: Don't use mmap on Windows
nik added a reviewer: ilya-biryukov. nik added a comment. Ping. I guess locking the file less helps also clangd?! https://reviews.llvm.org/D35200 ___ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D35200: Don't use mmap on Windows
yvvan added a comment. What do you think about that change? https://reviews.llvm.org/D35200 ___ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[PATCH] D35200: Don't use mmap on Windows
yvvan created this revision.
Memory mapping does not make llvm faster (at least I don't see any difference).
It also allows llvm not to lock files which is sometimes quite important.
https://reviews.llvm.org/D35200
Files:
lib/Support/MemoryBuffer.cpp
Index: lib/Support/MemoryBuffer.cpp
===
--- lib/Support/MemoryBuffer.cpp
+++ lib/Support/MemoryBuffer.cpp
@@ -284,6 +284,10 @@
bool RequiresNullTerminator,
int PageSize,
bool IsVolatile) {
+#ifdef _WIN32
+ // Do not use mmap on Windows in order to avoid file locking
+ return false;
+#endif
// mmap may leave the buffer without null terminator if the file size changed
// by the time the last page is mapped in, so avoid it if the file size is
// likely to change.
Index: lib/Support/MemoryBuffer.cpp
===
--- lib/Support/MemoryBuffer.cpp
+++ lib/Support/MemoryBuffer.cpp
@@ -284,6 +284,10 @@
bool RequiresNullTerminator,
int PageSize,
bool IsVolatile) {
+#ifdef _WIN32
+ // Do not use mmap on Windows in order to avoid file locking
+ return false;
+#endif
// mmap may leave the buffer without null terminator if the file size changed
// by the time the last page is mapped in, so avoid it if the file size is
// likely to change.
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