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internal/poll: raise Linux's maxCopyFileRangeRound to MAX_RW_COUNT

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Change-Id: I23c0c850ba57e7a49b78159d9293d1d25e1d2340
Reviewed-on: https://go-review.googlesource.com/c/go/+/606637
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Commit-Queue: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Andy Pan 2024-08-19 14:06:40 +08:00 committed by Gopher Robot
parent 1fd8557249
commit 6fb6ace308
1 changed files with 8 additions and 2 deletions
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10
src/internal/poll/copy_file_range_linux.go
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@ -22,13 +22,19 @@ var isKernelVersionGE53 = sync.OnceValue(func() bool {
return major > 5 || (major == 5 && minor >= 3)
})
const maxCopyFileRangeRound = 1 << 30
// For best performance, call copy_file_range() with the largest len value
// possible. Linux sets up a limitation of data transfer for most of its I/O
// system calls, as MAX_RW_COUNT (INT_MAX & PAGE_MASK). This value equals to
// the maximum integer value minus a page size that is typically 2^12=4096 bytes.
// That is to say, it's the maximum integer value with the lowest 12 bits unset,
// which is 0x7ffff000.
const maxCopyFileRangeRound = 0x7ffff000
func handleCopyFileRangeErr(err error, copied, written int64) (bool, error) {
switch err {
case syscall.ENOSYS:
// copy_file_range(2) was introduced in Linux 4.5.
// Go supports Linux >= 2.6.33, so the system call
// Go supports Linux >= 3.2, so the system call
// may not be present.
//
// If we see ENOSYS, we have certainly not transferred